GRE Math : How to find a rational number from an exponent

Study concepts, example questions & explanations for GRE Math

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Example Questions

Example Question #31 : Exponents

Quantitative Comparison: Compare Quantity A and Quantity B, using additional information centered above the two quantities if such information is given.

 

Quantity A             Quantity B

     43                              34 

Possible Answers:

The two quantities are equal.

Quantity A is greater.

The answer cannot be determined from the information given.

Quantity B is greater.

Correct answer:

Quantity B is greater.

Explanation:

In order to determine the relationship between the quantities, solve each quantity.

4is 4 * 4 * 4 = 64

34 is 3 * 3 * 3 * 3 = 81

Therefore, Quantity B is greater.

Example Question #32 : Exponents

Quantity A:

Quantity B:

Possible Answers:

The relationship cannot be determined from the information given. 

Quantity A is greater.

The two quantities are equal.

Quantity B is greater.

Correct answer:

Quantity B is greater.

Explanation:

(–1) 137= –1   

–1 < 0

(–1) odd # always equals –1.

(–1) even # always equals +1.

Example Question #34 : Algebra

 

Possible Answers:

Correct answer:

Explanation:

Anything raised to negative power means  over the base raised to the postive exponent. 

Example Question #38 : Algebra

Which of the following is not the same as the others?

Possible Answers:

Correct answer:

Explanation:

Let's all convert the bases to .

 This one may be intimidating but .

Therefore, 

 is not like the answers so this is the correct answer.

Example Question #41 : Gre Quantitative Reasoning

Simplify

Possible Answers:

Correct answer:

Explanation:

Whenever you see lots of multiplication (e.g. exponents, which are notation for repetitive multiplication) separated by addition or subtraction, a common way to transform the expression is to factor out common terms on either side of the + or - sign. That allows you to create more multiplication, which is helpful in reducing fractions or in reducing the addition/subtraction to numbers you can quickly calculate by hand as you'll see here.

 

So let's factor a .

We have .

And you'll see that the addition inside parentheses becomes quite manageable, leading to the final answer of 

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