Math 1 Quiz: No Solution And Infinite Solutions
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No Solution And Infinite SolutionsQuestion 1 of 19

When solving 2(3x+1)+4=6x+a2(3x + 1) + 4 = 6x + a, a student finds that the xx-terms cancel out, leaving 6=a6 = a. The student concludes this means x=a60x = \frac{a-6}{0}, which is undefined, so there's no solution. What is wrong with this reasoning?

The student should solve for aa first before determining the solution set; this approach confuses the parameter with the variable
The student incorrectly expanded; the proper expansion should give 6x+6=6x+a6x + 6 = 6x + a, leading to different conclusions
The student's algebra is correct, but a60\frac{a-6}{0} being undefined actually indicates infinitely many solutions exist
The student should recognize that 6=a6 = a when a=6a = 6 gives infinitely many solutions, not no solution
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Math 1 Quiz

Math 1 Quiz: No Solution And Infinite Solutions

Practice No Solution And Infinite Solutions in Math 1 with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.

What this quiz covers

This quiz focuses on No Solution And Infinite Solutions, giving you a quick way to practice the rules, question types, and explanations that matter most for Math 1.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

All questions

Question 1

When solving 2(3x+1)+4=6x+a2(3x + 1) + 4 = 6x + a, a student finds that the xx-terms cancel out, leaving 6=a6 = a. The student concludes this means x=a60x = \frac{a-6}{0}, which is undefined, so there's no solution. What is wrong with this reasoning?

  1. The student should solve for aa first before determining the solution set; this approach confuses the parameter with the variable
  2. The student incorrectly expanded; the proper expansion should give 6x+6=6x+a6x + 6 = 6x + a, leading to different conclusions
  3. The student's algebra is correct, but a60\frac{a-6}{0} being undefined actually indicates infinitely many solutions exist
  4. The student should recognize that 6=a6 = a when a=6a = 6 gives infinitely many solutions, not no solution (correct answer)
Explanation: When solving linear equations, you need to carefully interpret what it means when variables cancel out. This question tests your understanding of the relationship between parameters and solution sets. Let's work through this systematically. Starting with 2(3x+1)+4=6x+a2(3x + 1) + 4 = 6x + a, expand the left side: 6x+2+4=6x+a6x + 2 + 4 = 6x + a, which simplifies to 6x+6=6x+a6x + 6 = 6x + a. Subtracting 6x6x from both sides gives 6=a6 = a. Here's the key insight: when the variable terms cancel out, you're left with a statement about the parameter aa. If a=6a = 6, then 6=66 = 6 is always true, regardless of what xx equals. This means every real number is a solution—infinitely many solutions exist. If a6a ≠ 6, then you get a false statement like 6=56 = 5, meaning no solution exists. Choice A is wrong because the student's approach of analyzing when terms cancel is actually correct—it's the interpretation that's flawed. Choice B is incorrect because the expansion 6x+6=6x+a6x + 6 = 6x + a matches what the student found (6=a6 = a after canceling). Choice C makes the opposite error: when a6a ≠ 6, the undefined expression indicates no solution, not infinitely many. Choice D correctly identifies that 6=a6 = a specifically when a=6a = 6 creates infinitely many solutions, not no solution. Study tip: When variables cancel in linear equations, check if the remaining statement is true (infinitely many solutions) or false (no solution). Don't immediately assume "undefined" means no solution.

Question 2

Consider the equation 4(x+3)2x=2(x+k)4(x + 3) - 2x = 2(x + k). For what value of kk does this equation have infinitely many solutions, and what error might lead a student to incorrectly conclude there's no solution?

  1. k=6k = 6; students might incorrectly assume that equal xx-coefficients always mean no solution exists
  2. k=3k = 3; students might mistake the identical coefficients as indicating parallel lines with no intersection
  3. k=6k = 6; students might incorrectly distribute and conclude 12=012 = 0 represents no solution (correct answer)
  4. k=12k = 12; students might confuse the distributive property and incorrectly simplify the constant terms
Explanation: When you encounter linear equations that might have infinitely many solutions, you're looking for cases where both sides simplify to identical expressions. This happens when the equation becomes a true statement like 12=1212 = 12. Let's solve this systematically. Starting with 4(x+3)2x=2(x+k)4(x + 3) - 2x = 2(x + k), distribute on the left side: 4x+122x=2(x+k)4x + 12 - 2x = 2(x + k), which simplifies to 2x+12=2(x+k)2x + 12 = 2(x + k). Now distribute on the right: 2x+12=2x+2k2x + 12 = 2x + 2k. Subtracting 2x2x from both sides gives us 12=2k12 = 2k, so k=6k = 6. When k=6k = 6, the original equation becomes 2x+12=2x+122x + 12 = 2x + 12, which is always true regardless of xx's value—hence infinitely many solutions. Looking at the wrong answers: Choice A gives the correct value k=6k = 6 but describes an incorrect misconception about equal coefficients. Choice B incorrectly states k=3k = 3, which would give us 12=612 = 6—clearly false, meaning no solution exists. Choice D incorrectly claims k=12k = 12, which would result in 12=2412 = 24, also impossible. Choice C correctly identifies k=6k = 6 and describes a realistic student error: incorrectly distributing to get something like 12=012 = 0 and concluding there's no solution, when the correct simplification actually shows the equation is always true. Study tip: For linear equations, infinitely many solutions occur when you get a true statement (like 12=1212 = 12), while no solution means you get a false statement (like 12=012 = 0).

Question 3

A student is solving the equation 3(2x4)=6x+k3(2x - 4) = 6x + k and claims that for a certain value of kk, the equation has infinitely many solutions. Which value of kk supports this claim, and what fundamental property makes this possible?

  1. k=12k = -12; the equation becomes an identity when both sides are algebraically equivalent (correct answer)
  2. k=12k = 12; the equation has infinitely many solutions when the constant terms are equal
  3. k=0k = 0; the equation becomes homogeneous, which always yields infinitely many solutions
  4. k=6k = -6; the equation has infinitely many solutions when the right side coefficient equals half the left side
Explanation: Expanding the left side: 3(2x4)=6x123(2x - 4) = 6x - 12. The equation becomes 6x12=6x+k6x - 12 = 6x + k. For infinitely many solutions, both sides must be identical, so k=12k = -12. This creates the identity 6x12=6x126x - 12 = 6x - 12, which is true for all values of xx. Choice B gives 6x12=6x+126x - 12 = 6x + 12, which simplifies to 12=12-12 = 12 (no solution). Choice C gives 6x12=6x6x - 12 = 6x, which simplifies to 12=0-12 = 0 (no solution). Choice D gives 6x12=6x66x - 12 = 6x - 6, which simplifies to 12=6-12 = -6 (no solution).

Question 4

A linear equation of the form mx+n=px+qmx + n = px + q is being analyzed. Under what conditions will this equation have infinitely many solutions, and what does this reveal about the geometric relationship?

  1. m=pm = p and n=qn = q; the equation represents two identical lines overlapping completely (correct answer)
  2. m=pm = p and nqn ≠ q; the equation represents two parallel lines that never intersect
  3. mpm ≠ p and n=qn = q; the equation represents two lines with the same yy-intercept
  4. mp=nq\frac{m}{p} = \frac{n}{q} and both ratios are defined; the equations are proportionally equivalent
Explanation: For infinitely many solutions, the equation must be an identity (true for all xx values). This occurs when mx+n=px+qmx + n = px + q simplifies to 0=00 = 0. Rearranging: (mp)x=qn(m-p)x = q-n. For this to be true for all xx, we need mp=0m-p = 0 and qn=0q-n = 0, which means m=pm = p and n=qn = q. Geometrically, this means both sides represent the same line. Choice B describes parallel lines (no solution), choice C describes intersecting lines (one solution), and choice D incorrectly suggests proportional coefficients guarantee infinite solutions without requiring equality.

Question 5

Consider the equation 3(2x1)6x=mx33(2x - 1) - 6x = mx - 3 where mm is a constant. For what value of mm will this equation have infinitely many solutions?

  1. m=0m = 0 (correct answer)
  2. m=3m = 3
  3. m=6m = 6
  4. m=3m = -3
Explanation: Simplifying the left side: 3(2x1)6x=6x36x=33(2x - 1) - 6x = 6x - 3 - 6x = -3. The equation becomes 3=mx3-3 = mx - 3, or 0=mx0 = mx. For infinitely many solutions, we need this to be an identity. When m=0m = 0, we get 0=00 = 0, which is always true. Other values of m would either give a unique solution (x=0x = 0) or no solution.

Question 6

The equation 3(x+2)12=px63(x + 2) - 12 = px - 6 has infinitely many solutions. What is the value of pp?

  1. p=3p = 3 (correct answer)
  2. p=0p = 0
  3. p=3p = -3
  4. p=6p = 6
Explanation: Expanding the left side: 3(x+2)12=3x+612=3x63(x + 2) - 12 = 3x + 6 - 12 = 3x - 6. For infinitely many solutions, both sides must be identical: 3x6=px63x - 6 = px - 6. This requires p=3p = 3. With any other value of p, the equation would have either one solution or no solution.

Question 7

Two students are solving 7x14=7(x+k)7x - 14 = 7(x + k) for different values of kk. Student A finds infinitely many solutions, while Student B finds no solution. If both students solved correctly, what can be concluded about their values of kk?

  1. This scenario is impossible because the equation cannot have different solution types
  2. Student A used k=2k = 2 and Student B used any other value
  3. Student A used k=2k = -2 and Student B used k=2k = 2
  4. Student A used k=2k = -2 and Student B used any other value (correct answer)
Explanation: When you encounter an equation with a parameter like kk, think about how different values of that parameter affect the number of solutions. Linear equations can have exactly one solution, infinitely many solutions, or no solution depending on how they simplify. Let's expand the given equation: 7x14=7(x+k)7x - 14 = 7(x + k) becomes 7x14=7x+7k7x - 14 = 7x + 7k. Subtracting 7x7x from both sides gives us 14=7k-14 = 7k, so k=2k = -2. When k=2k = -2, we get 14=14-14 = -14, which is always true regardless of the value of xx. This means infinitely many solutions—every real number satisfies the equation. This is what Student A encountered. For any other value of kk, we'd have 14=7k-14 = 7k where 7k147k \neq -14. This creates a contradiction (like 14=0-14 = 0 if k=0k = 0), meaning no value of xx can satisfy the equation. This gives Student B no solution. Now for the wrong answers: Choice A is incorrect because linear equations absolutely can have different solution types depending on parameters. Choice B incorrectly states that k=2k = 2 gives infinitely many solutions, but k=2k = 2 would give 14=14-14 = 14, which is impossible. Choice C has the values backwards—k=2k = 2 gives no solution, not infinitely many. Study tip: When solving parametric equations, always check what happens when coefficients of the variable terms are equal on both sides. The relationship between the constant terms determines whether you get infinitely many solutions (constants equal) or no solution (constants unequal).

Question 8

When does the equation m(x+2)=mx+2m+nm(x + 2) = mx + 2m + n have no solution, and what common misconception might lead students to the wrong conclusion?

  1. Never; this equation always simplifies to 0=n0 = n, giving either infinitely many or no solutions
  2. When n0n ≠ 0; students might think n=0n = 0 gives no solution because 'zero equals zero' (correct answer)
  3. When n=0n = 0; students might incorrectly believe that identical variable terms always indicate no solution
  4. When m=0m = 0 and n0n ≠ 0; students might overlook the special case where the leading coefficient vanishes
Explanation: Expanding the left side: m(x+2)=mx+2mm(x + 2) = mx + 2m. The equation becomes mx+2m=mx+2m+nmx + 2m = mx + 2m + n. Subtracting mx+2mmx + 2m from both sides gives 0=n0 = n. If n=0n = 0, we get 0=00 = 0 (infinitely many solutions). If n0n ≠ 0, we get 0=nonzero0 = \text{nonzero} (no solution). Students often confuse 0=00 = 0 as meaning 'no solution' because they think it's 'meaningless,' when actually it means every xx value works. Choice A correctly identifies the simplification but incorrectly states it never has no solution. Choices C and D contain incorrect conditions and misconceptions.

Question 9

A student is analyzing when 2x+63=2x+k3\frac{2x+6}{3} = \frac{2x+k}{3} has no solution versus infinitely many solutions. Which statement best explains the key distinction?

  1. If k=6k = 6, there are infinitely many solutions; if k6k ≠ 6, there are no solutions (correct answer)
  2. If k=6k = 6, there are infinitely many solutions; if k6k ≠ 6, there is exactly one solution
  3. The equation always has infinitely many solutions regardless of kk since the xx-coefficients are identical
  4. The equation can never have no solution; it either has one solution or infinitely many depending on kk
Explanation: Since both sides have the same denominator, we can multiply by 3: 2x+6=2x+k2x + 6 = 2x + k. Subtracting 2x2x from both sides gives 6=k6 = k. If k=6k = 6, we get 6=66 = 6, which is always true (infinitely many solutions). If k6k ≠ 6, we get a false statement like 6=56 = 5, which means no solution exists. Choice B incorrectly suggests there could be exactly one solution, but since the xx-coefficients are equal, we can never isolate xx to get a unique value. Choices C and D misunderstand the relationship between the parameter kk and the solution types.

Question 10

A student claims that the equation 5x+7=5x+75x + 7 = 5x + 7 has exactly one solution because 'both sides are equal.' What is the error in this reasoning, and what is the actual solution set?

  1. The student correctly identified one solution; the equation has exactly one solution at x=0x = 0
  2. The equation simplifies to 0=00 = 0; this creates a contradiction, resulting in no solution
  3. The equation is an identity; every real number satisfies it, so there are infinitely many solutions (correct answer)
  4. The equation represents parallel lines; since they never intersect, there is no solution to find
Explanation: When you encounter equations where both sides appear identical, you're dealing with a special type of linear equation that requires careful analysis of what happens when you try to solve it. Let's work through this equation step by step. Starting with 5x+7=5x+75x + 7 = 5x + 7, subtract 5x5x from both sides: 7=77 = 7. This simplifies to a true statement that doesn't depend on xx at all. When an equation reduces to a statement that's always true (like 7=77 = 7 or 0=00 = 0), it means the original equation is called an identity—it's satisfied by every possible value of xx. You can substitute any real number for xx and the equation remains true. Looking at the wrong answers: Choice A incorrectly assumes there's one solution at x=0x = 0, but substituting any other value like x=3x = 3 still gives you 22=2222 = 22. Choice B correctly notes that equations can simplify to 0=00 = 0, but wrongly calls this a contradiction—it's actually a confirmation that all values work. A contradiction would be something like 0=50 = 5. Choice D mentions parallel lines, which is irrelevant since this isn't a system of equations or a geometric problem. The key insight is recognizing the difference between identities (infinitely many solutions), contradictions (no solutions), and conditional equations (exactly one solution). When you simplify an equation and get a true statement with no variables, you have an identity with infinitely many solutions.

Question 11

Consider the system of equations: {ax+3y=122x+by=8\begin{cases} ax + 3y = 12 \\ 2x + by = 8 \end{cases}. If this system has no solution, which relationship between aa and bb must be satisfied?

  1. a=6a = 6 and b=32b = \frac{3}{2}, creating parallel lines with different intercepts
  2. a=32a = \frac{3}{2} and b=4b = 4, making the coefficient ratios proportional but not the constants
  3. a=32a = \frac{3}{2} and b=4b = 4, creating identical slopes but different yy-intercepts (correct answer)
  4. a=23a = \frac{2}{3} and b=43b = \frac{4}{3}, ensuring the determinant of coefficients equals zero
Explanation: For no solution, the lines must be parallel (same slope) but not identical. Converting to slope-intercept form: first equation gives y=a3x+4y = -\frac{a}{3}x + 4, second gives y=2bx+8by = -\frac{2}{b}x + \frac{8}{b}. For parallel lines: a3=2b-\frac{a}{3} = -\frac{2}{b}, so ab=6ab = 6. With a=32a = \frac{3}{2} and b=4b = 4: ab=6ab = 6 ✓. The yy-intercepts are 44 and 22, which are different, confirming parallel but distinct lines. Choice A gives intersecting lines, choice B restates C without the slope explanation, and choice D gives values where ab=896ab = \frac{8}{9} ≠ 6.

Question 12

The equation ax5=3x+bax - 5 = 3x + b has infinitely many solutions. If aa and bb are both integers, what is the sum a+ba + b?

  1. a+b=8a + b = -8, since a=3a = -3 and b=5b = -5 make both sides of the equation identical
  2. a+b=8a + b = 8, since a=3a = 3 and b=5b = 5 create equivalent expressions on both sides
  3. a+b=0a + b = 0, since a=3a = -3 and b=3b = 3 result in identical simplified forms
  4. a+b=2a + b = -2, since a=3a = 3 and b=5b = -5 make the equation an identity (correct answer)
Explanation: When a linear equation has infinitely many solutions, it means both sides are identical expressions—no matter what value you substitute for the variable, the equation will always be true. This happens when the equation simplifies to something like 0=00 = 0. To find when ax5=3x+bax - 5 = 3x + b has infinitely many solutions, rearrange it to standard form: ax3x=b+5ax - 3x = b + 5, or (a3)x=b+5(a-3)x = b + 5. For this to be true for all values of xx, both the coefficient of xx and the constant term must equal zero. This means a3=0a - 3 = 0 and b+5=0b + 5 = 0, giving us a=3a = 3 and b=5b = -5. Therefore, a+b=3+(5)=2a + b = 3 + (-5) = -2. Let's check each option: Choice A claims a=3a = -3 and b=5b = -5, but if a=3a = -3, then 3x5=3x5-3x - 5 = 3x - 5 simplifies to 6x=0-6x = 0, which only has one solution (x=0x = 0). Choice B suggests a=3a = 3 and b=5b = 5, making the equation 3x5=3x+53x - 5 = 3x + 5, which simplifies to 5=5-5 = 5—this is never true, so there are no solutions. Choice C proposes a=3a = -3 and b=3b = 3, giving 3x5=3x+3-3x - 5 = 3x + 3, which simplifies to 6x=8-6x = 8—again, only one solution. Choice D correctly identifies a=3a = 3 and b=5b = -5, making both sides identical: 3x5=3x53x - 5 = 3x - 5. Remember: for infinitely many solutions, make both sides of the equation completely identical by setting the coefficients and constants equal to each other.

Question 13

The equation 2x+63=ax+b3+c\frac{2x + 6}{3} = \frac{ax + b}{3} + c has no solution when solved for xx. If a=2a = 2, what must be true about the relationship between bb and cc?

  1. b6b ≠ 6 and cc can be any real number except zero
  2. b=6b = 6 and c0c ≠ 0, creating a contradiction in the constant terms (correct answer)
  3. b+3c=6b + 3c = 6 and c0c ≠ 0, ensuring the simplified equation is inconsistent
  4. b6b ≠ 6 and c=0c = 0, making the variable coefficients unequal while constants are equal
Explanation: Multiply both sides by 3: 2x+6=2x+b+3c2x + 6 = 2x + b + 3c. Subtracting 2x2x from both sides: 6=b+3c6 = b + 3c. For no solution, we need the variable terms to be identical but the constant terms different. Since the xx-coefficients are already equal (both 2), we need 6b+3c6 ≠ b + 3c. However, if b=6b = 6 and c0c ≠ 0, then b+3c=6+3c6b + 3c = 6 + 3c ≠ 6, creating the contradiction 6=6+3c6 = 6 + 3c where 3c03c ≠ 0. The other choices either allow solutions to exist or don't guarantee the no-solution condition.

Question 14

The system {3x+2y=6kx+4y=12\begin{cases} 3x + 2y = 6 \\ kx + 4y = 12 \end{cases} has infinitely many solutions. What is the value of kk, and what geometric principle explains this result?

  1. k=9k = 9; the coefficient relationships ensure the system has dependent equations with identical solutions
  2. k=3k = 3; both equations have the same xx-coefficient, ensuring they represent the same line
  3. k=1.5k = 1.5; the ratio of coefficients creates proportional equations representing overlapping lines
  4. k=6k = 6; the second equation is a scalar multiple of the first, creating identical lines (correct answer)
Explanation: When a system of linear equations has infinitely many solutions, it means the equations represent the same line—they're geometrically identical. This happens when one equation is a scalar multiple of the other. To find when our system has infinitely many solutions, we need the second equation to be a multiple of the first. Looking at equation 1: 3x+2y=63x + 2y = 6. If we multiply every term by 2, we get: 6x+4y=126x + 4y = 12. This matches the form of equation 2 (kx+4y=12kx + 4y = 12) when k=6k = 6. Let's verify: when k=6k = 6, both equations become equivalent forms of the same line. The second equation 6x+4y=126x + 4y = 12 is exactly twice the first equation 3x+2y=63x + 2y = 6, so they represent identical lines with infinitely many intersection points. Choice A is wrong because k=9k = 9 would give us 9x+4y=129x + 4y = 12, which isn't a multiple of the first equation. Choice B incorrectly assumes equal x-coefficients create the same line—this isn't true since the y-coefficients and constants also matter. Choice C gives k=1.5k = 1.5, resulting in 1.5x+4y=121.5x + 4y = 12, which also isn't proportional to equation 1. Study tip: For systems with infinitely many solutions, check if one equation is a scalar multiple of the other by comparing the ratios of corresponding coefficients. All ratios (x-coefficient, y-coefficient, and constant) must be equal: k3=42=126=2\frac{k}{3} = \frac{4}{2} = \frac{12}{6} = 2, giving k=6k = 6.

Question 15

Marcus is solving the equation 3(x4)+2x=5x123(x - 4) + 2x = 5x - 12. After distributing and combining like terms, he obtains 5x12=5x125x - 12 = 5x - 12. What conclusion should Marcus draw about this equation?

  1. The equation has no solution because both sides are identical
  2. The equation has infinitely many solutions because the statement is always true (correct answer)
  3. The equation has exactly one solution at x=0x = 0
  4. The equation has exactly one solution at x=12x = 12
Explanation: When an equation simplifies to an identity (like 5x12=5x125x - 12 = 5x - 12), it means the original equation is true for all values of x, resulting in infinitely many solutions. Choice A is incorrect because identical sides indicate an identity, not no solution. Choices C and D are incorrect because there isn't a unique solution value.

Question 16

Sarah claims that the equation 4x7=4(x+2)154x - 7 = 4(x + 2) - 15 has no solution. Which statement best explains whether Sarah is correct?

  1. Sarah is incorrect; the equation has infinitely many solutions because it simplifies to 7=7-7 = -7
  2. Sarah is incorrect; the equation has infinitely many solutions because it simplifies to 4x7=4x74x - 7 = 4x - 7 (correct answer)
  3. Sarah is correct; the equation has no solution because the coefficients are the same
  4. Sarah is correct; the equation has no solution because it simplifies to 0=80 = 8
Explanation: Expanding the right side: 4(x+2)15=4x+815=4x74(x + 2) - 15 = 4x + 8 - 15 = 4x - 7. The equation becomes 4x7=4x74x - 7 = 4x - 7, which is an identity true for all values of x, meaning infinitely many solutions. Choice A gives the wrong simplified form. Choice B correctly identifies both the simplified form and the conclusion. Choices C and D incorrectly conclude there's no solution.

Question 17

Which of the following equations has the same solution set as 2x+5=2x+52x + 5 = 2x + 5?

  1. x+3=x1x + 3 = x - 1
  2. 3x=03x = 0
  3. 4x1=4x14x - 1 = 4x - 1 (correct answer)
  4. x=5x = 5
Explanation: This question tests your understanding of solution sets and equivalent equations. The solution set of an equation is the collection of all values that make the equation true. Let's analyze the given equation 2x+5=2x+52x + 5 = 2x + 5. Notice that both sides are identical, so this equation is true for every possible value of x. This is called an identity, and its solution set includes all real numbers. Now we need to find which answer choice has the same solution set (all real numbers). Choice C, 4x1=4x14x - 1 = 4x - 1, is correct because it's also an identity. Just like the original equation, both sides are identical, making it true for any value of x. The solution set is all real numbers. Choice A, x+3=x1x + 3 = x - 1, is wrong because if you subtract x from both sides, you get 3=13 = -1, which is never true. This equation has no solution (empty solution set). Choice B, 3x=03x = 0, is wrong because it has exactly one solution: x=0x = 0. Only when x equals zero does this equation hold true. Choice D, x=5x = 5, is wrong because it also has exactly one solution: x=5x = 5. Only this specific value satisfies the equation. Study tip: When comparing solution sets, look for the type of equation first. Identities (where both sides are identical) always have infinitely many solutions, contradictions have no solutions, and most other equations have specific solutions. Match the types, not just the appearance.

Question 18

Elena is solving 5x+8=5x25x + 8 = 5x - 2. After subtracting 5x5x from both sides, she gets 8=28 = -2. What does this result indicate about the original equation?

  1. The equation has infinitely many solutions because the variable was eliminated
  2. The equation has one solution where x=8x = 8 or x=2x = -2
  3. The equation has no solution because 8=28 = -2 is a false statement (correct answer)
  4. The equation has no solution because the coefficients of xx are equal
Explanation: When solving linear equations, you might encounter three possible outcomes: one solution, infinitely many solutions, or no solution. The key is recognizing what happens when you eliminate the variable through algebraic manipulation. Elena correctly subtracted 5x5x from both sides of 5x+8=5x25x + 8 = 5x - 2, which eliminated the variable entirely and left her with 8=28 = -2. Since this statement is mathematically false (8 will never equal -2), the original equation has no solution. This means there's no value of xx that could make the original equation true. Choice A incorrectly assumes that eliminating the variable always means infinitely many solutions. While variable elimination does occur with infinitely many solutions, you get a true statement like 3=33 = 3, not a false one. Choice B misunderstands the meaning of 8=28 = -2 entirely—this isn't telling us that xx equals 8 or -2, but rather showing us an impossible statement. Choice D identifies a true observation (the coefficients of xx are equal) but gives the wrong reasoning. Equal coefficients don't automatically mean no solution—they just mean the variable will be eliminated, and then you must check whether the resulting statement is true or false. Remember this pattern: when solving an equation eliminates the variable, check what remains. If you get a true statement (like 5=55 = 5), there are infinitely many solutions. If you get a false statement (like 8=28 = -2), there are no solutions.

Question 19

A student incorrectly concludes that 6x9=2(3x4)16x - 9 = 2(3x - 4) - 1 has no solution. What error did the student likely make?

  1. The student forgot to distribute the 2 on the right side correctly
  2. The student incorrectly simplified 2(3x4)12(3x - 4) - 1 to 6x96x - 9 instead of 6x76x - 7
  3. The student correctly found that the equation simplifies to 9=9-9 = -9 but misinterpreted this as no solution
  4. The student incorrectly simplified 2(3x4)12(3x - 4) - 1 to 6x76x - 7 instead of 6x96x - 9 (correct answer)
Explanation: Let's check: 2(3x4)1=6x81=6x92(3x - 4) - 1 = 6x - 8 - 1 = 6x - 9. The equation becomes 6x9=6x96x - 9 = 6x - 9, which has infinitely many solutions. If the student got 6x76x - 7 instead of 6x96x - 9, they would have 6x9=6x76x - 9 = 6x - 7, leading to 9=7-9 = -7 (no solution). Choice D correctly identifies this computational error.