Exponential Operations - ISEE Upper Level Quantitative Reasoning

Card 0 of 348

Question

Simplify the expression:

$6x^{4} + 8x^{3} - 4x^{2}$

Answer

$6x^{4} + 8x^{3} - 4x^{2}$

$=2x^{2}(3x^{2}+4x-2)$

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Question

Simplify:

Answer

In order to add exponential terms, both the base and the exponent must be the same. So we can write:

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Question

Evaluate:

$\frac{x^0+y^0+1}{x^0-y^0-1}$

Answer

Based on the zero-exponent rule we have:

That means any non-zero number raised to the zero power is equal to . So we can write:

$\frac{1+1+1}{1-1-1}=\frac{3}{-1}=-3$

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Question

Which of the following is equivalent to the expression below?

$4^{x}\cdot2^{5}$

Answer

When exponents are multiplied by one another, and the base is the same, the exponents can be added together.

The first step is to try to create a common base.

$4^{x}\cdot2^{5}$

Given that the square of 2 is for, the expression can be rewritten as:

$2^{2}^{x}\cdot 2^{5}$

$2^{2x+5}$

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Question

What is the value of the expression:

$x^{3}\cdotx^{y}\cdot x^{2+y}$

Answer

When values, having the same base, are multiplied by one another, the exponents are added together and the base stays the same.

Thus,

$x^{3}\cdotx^{y}\cdot x^{2+y}$

is equal to

$x^{4}\cdotx^{y+2}$

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Question

Simplify: $x^{7}\cdot2x^{3}$

Answer

When multiplying exponents, the exponents are added together. Thus, 3 and 7 are added together for a sum of 10. In this problem, the "2" becomes a coefficient in front of the x. Therefore, the correct answer is:

$2x^{10}$

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Question

Simplify the expression:

$3x^{4}+6x^{3}-9x^{2}$

Answer

To simplify this problem we need to factor out a

$3x^{4}+6x^{3}-9x^{2}$

$=3x^{2}(x^{2}+2x-3)$

We can do this because multiplying exponents is the same as adding them. Therefore,

$=3x^{2}(x^{2}+2x-3)$

$=3x^2 \cdot x^2 +3x^2\cdot2x -3x^2\cdot3=3x^{2+2}+3\cdot2x^{2+1}-3\cdot 3x^2$

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Question

Simplify:

$x^{6}\cdot x^{4}$

Answer

When multiplying exponents, the exponents are added together.

$x^{6}\cdot x^{4} = x^{6+4}=x^{10}$

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Question

Simplify:

$2x^{2}\cdot 3x^{4}$

Answer

When multiplying exponents, the exponents are added together.

$2x^{2}\cdot 3x^{4}=6x^{2+4}=6x^{6}$

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Question

Solve: $3^5 \cdot 3^{-8}$

Answer

It is not necessary to evaluate both terms and multiply.

According to the rules of exponents, when we have the same bases raised to some power that are multiplied with each other, we can add the powers.

$3^5 \cdot 3^{-8} = 3^{5+( -8)} = 3^{-3}$

This term can be rewritten as a fraction.

$3^{-3 } = \frac{1}{3^3} = \frac{1}{27}$

The answer is: $\frac{1}{27}$

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Question

Simplify:

$(6a^3)(\frac{1}{3}a^2)$

Answer

Based on the product rule for exponents in order to multiply two exponential terms with the same base, add their exponents:

$(x)^a(x)^b=x^{a+b}$

So we can write:

$(6a^3)\left(\frac{1}{3}a^2\right)=\left(\frac{6}{3}\right)\times a^{3+2}=2a^5$

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Question

$\dpi{100} (7-4)^{3}=$

Answer

Subtract the numbers inside the parentheses first. This leaves you with 3, which you then raise to the 3rd power:

$\dpi{100} 3\times 3\times 3=27$

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Question

Evaluate:

$\frac{1^{0}+2 ^{0}+3 ^{0}}{6^{0}}$

Answer

Any nonzero number taken to the power of 0 is equal to 1, so

$\frac{1^{0}+2 ^{0}+3 ^{0}}{6^{0}} = \frac{1+1+1}{1} = \frac{3}{1} = 3$

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Question

Multiply:

$(4r^{2} - 7) (5r^{2}+ 8 )$

Answer

Use the FOIL method:

$(4r^{2} - 7) (5r^{2}+ 8 )$

$=4r^{2} \cdot 5r^{2} + 4r^{2} \cdot 8 -7 \cdot 5r^{2} -7 \cdot 8$

$=4\cdot 5 \cdot r^{2}\cdot r^{2} + 4\cdot 8\cdot r^{2} -7 \cdot 5\cdot r^{2} -7 \cdot 8$

$=20 \cdot r^{2+2} + 32r^{2} -35r^{2} -56$

$=20r^{4} +\left ( 32-35 \right )r^{2} -56$

$=20r^{4} -3r^{2} -56$

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Question

Simplify:

$(x^{2\sqrt{2}})^{3\sqrt{2}}$

Answer

Based on the power rule, we know that in order to raise a power to a power we need to multiply the exponents, i.e.

$(x^{m})^{n}=x^{m\times n}$ .

$(x^{2\sqrt{2}})^{3\sqrt{2}}=x^{2\sqrt{2}\times 3\sqrt{2}}=x^{2\times 3\times 2}=x^{12}$

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Question

Simplify:

$(\frac{12x^{3}}{3x^{-1}})^{4}$

Answer

The Negative Exponent Rule says $a^{-n}=\frac{1}{a^n}$ .

$(\frac{12x^{3}}{3x^{-1}})^{4}=(\frac{12}{3}\times x^{3+1})^{4}=(4x^4)^{4}$

The power rule says that, in order to raise a power to a power, we need to multiply the exponents, i.e. $(x^{m})^{n}=x^{m\times n}$ .

$(\frac{12x^{3}}{3x^{-1}})^{4}=(4x^4)^{4}=4^4\times x^{4\times 4}=256x^{16}$

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Question

Simplify:

$(6a^3)(\frac{1}{3}a^2)$

Answer

Based on the product rule for exponents in order to multiply two exponential terms with the same base, add their exponents:

$(x)^a(x)^b=x^{a+b}$

So we can write:

$(6a^3)\left(\frac{1}{3}a^2\right)=\left(\frac{6}{3}\right)\times a^{3+2}=2a^5$

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Question

Evaluate:

$-x(x^3)^{2}$

Answer

Based on the power rule for exponents we can write:

$(a^m)^{n}=a^{m\times n}$

That means; to raise a power to a power we need to multiply the exponents. In addition, based on the product rule for exponents in order to multiply two exponential terms with the same base, we need to add their exponents:

$(x)^a(x)^b=x^{a+b}$

So we can write:

$-x(x^3)^{2}=-x(x^{3\times 2})=-x(x^6)=-x^{1+6}=-x^7$

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Question

Evaluate:

$-2x^2(x^{-3})^{3}$

Answer

Based on the negative exponent rule we have:

$a^{-n}=\frac{1}{a^n}$

which says negative exponents in the numerator get moved to the denominator and become positive exponents. And negative exponents in the denominator get moved to the numerator and become positive exponents. So we can write:

$-2x^2(x^{-3})^{3}=-2x^2\left(\frac{1}{x^3}\right)^{3}$

In addition, based on the power rule for exponents we can write:

$(a^m)^{n}=a^{m\times n}$

That means; to raise a power to a power we need to multiply the exponents. We also know that when a fraction is raised to a power, the numerator and the denominator are both raised to that power. So we can write:

$-2x^2(x^{-3})^{3}=-2x^2\left(\frac{1}{x^3}\right)^{3}=-2x^2\times \frac{1^3}{x^{3\times 3}}$

$=-2x^2\times \frac{1}{x^9}$

$=\frac{-2x^2}{x^9}$

$=-2x^{2-9}$

$=-2x^{-7}$

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Question

Evaluate:

$\frac{4x^2(x^3)^{3}}{8x^7}$

Answer

Based on the power rule for exponents we can write:

$(a^m)^{n}=a^{m\times n}$

That means; to raise a power to a power we need to multiply the exponents. In addition, based on the product rule for exponents, in order to multiply two exponential terms with the same base we need to add their exponents:

$(x)^a(x)^b=x^{a+b}$

So we can write:

$\frac{4x^2(x^3)^{3}}{8x^7}=\frac{4x^2(x^{3\times 3})}{8x^7}=\frac{4x^2\times x^9}{8x^7}=\left(\frac{4}{8}\right)\frac{x^{2+9}}{x^7}=\frac{1}{2}\cdot \frac{x^{11}}{x^7}$

in order to divide two exponents with the same base, we can keep the base and subtract the powers. So we get:

$\frac{4x^2(x^3)^{3}}{8x^7}=\frac{1}{2}\cdot \frac{x^{11}}{x^7}=\frac{1}{2}x^{11-7}=\frac{1}{2}x^4$

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