ACT Math : How to subtract polynomials

Study concepts, example questions & explanations for ACT Math

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Example Questions

Example Question #7 : Polynomials

Simplify:

Possible Answers:

Correct answer:

Explanation:

When subtracting polynomials, it's helpful to remember that the "minus sign" gets distributed. It's as if the two polynomials are being added and a -1 is in front of the second polynomial.

This -1 will get multiplied to all the terms in the second polynomial that is being subtracted from the first, so it becomes . You may note that by multiplying by -1, every term in the polynomial switches its original sign. The problem then becomes:

From here, in order to simplify, because there's no equal sign, it can be deduced that we are not working toward a solution for x. The original problem is presented as an expression so an expression as an answer will be expected. In order to work towards a final simplified expression, like terms must be collected. This will provide the final answer.

 

 

Example Question #1 : How To Subtract Polynomials

Simplify:

Possible Answers:

Correct answer:

Explanation:

Begin by distributing the subtraction of the second term in this question:

Now, you merely need to combine like terms:

Example Question #23 : Variables

Solve the equation 

Possible Answers:

Correct answer:

Explanation:

To answer this question, we are solving for the values of  that make this equation true.

To this, we need to get  on a side by itself so we can evaluate it. To do this, we first add  to both sides so that we can then begin to deal with the  value. So, for this data:

can also be written as . Therefore:

Now we can divide both sides by  and find the value of .

Therefore, the answer to this question is 

Example Question #2 : How To Subtract Polynomials

If , then what does  equal?

Possible Answers:

Correct answer:

Explanation:

To solve this equation, we substitute  in for every instance of  seen in the original equation .

Therefore the new equation would read 

Now we must square the expression . To do this, you must multiply the expression by itself. Therefore:

We must now plug in our new value for  into our original equation in place of .

Now we must distribute the  into . To do this, you multiply each expression within the parenthesis by :

Therefore, our answer is .

Example Question #13 : Polynomials

The expression  is equivalent to which of the following?

Possible Answers:

Correct answer:

Explanation:

To answer this question, we must distribute the  to the rest of the variables , , and  that are within the brackets.

To distribute a variable or number, you multiply that value with every other value within the brackets or parentheses. So, for this data:

We then simplify the expression by combining the variables we are multiplying together into expressions. For this data:

Be sure to keep all of your operations the same within the problem itself, unless the number being distributed is negative, which will then switch the signs with the brackets from positive to negative or negative to positive. 

Therefore, our answer is .

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