GRE Math : GRE Quantitative Reasoning

Study concepts, example questions & explanations for GRE Math

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Example Questions

Example Question #62 : Exponents

Which of the following is equal to ?

Possible Answers:

Correct answer:

Explanation:

First, multiply inside the parentheses: .

Then raise to the 7th power: .

Example Question #61 : Exponents

Simplify:

(6x^{2})^{3}\cdot x^{-7}\cdot 2x^{4}

Possible Answers:

6x^{2}

12x^{2}

Correct answer:

Explanation:

Remember, we add exponents when their bases are multiplied, and multiply exponents when one is raised to the power of another. Negative exponents flip to the denominator (presuming they originally appear in the numerator). 

(6x^{2})^{3}\cdot x^{-7}\cdot 2x^{4}

 

Example Question #11 : How To Multiply Exponents

 is a real number such that .

Quantity A:

 

Quantity B:

Possible Answers:

The two quantities are equal.

Quantity B is greater.

The relationship cannot be determined from the information given.

Quantity A is greater.

Correct answer:

The relationship cannot be determined from the information given.

Explanation:

(y2)(y4) = y2+4 = y6

Plug in two different values for y.

Plug in y = 1: y8 = y

Plug in y = 2: y8 > y

Since the results differ, the relationship cannot be determined from the information given.

Example Question #13 : How To Multiply Exponents

Evaluate:

Possible Answers:

\dpi{100} \small 81

\dpi{100} \small 30

\dpi{100} \small 24

\dpi{100} \small 78

\dpi{100} \small 27

Correct answer:

\dpi{100} \small 78

Explanation:

Can be simplified to: 

Capture2

Example Question #14 : How To Multiply Exponents

Simplify the following expression.

Possible Answers:

Correct answer:

Explanation:

To solve this problem, we must first understand some of the basic concepts of exponents. When multiplying exponents with the same base, one would simply add the powers together with the same base to obtain the result. For example, .

When raising exponents to a certain power, one would simply multiply the power the exponent is being raised to with the exponent itself to obtain the new exponent. The base also gets raised to the same power as it normally would and the new exponent gets put on afterward. For example .

Now that we have covered the basic concepts of exponent manipulation, we can now solve the problem. The top part of the expression give to us is . As we have stated before, when an exponent is raised to a certain power, you simply multiply the power and the exponent together. This results in .

 

The new expression becomes .

 

Solving for the denominator of the equation, we previously stated that when multiplying exponents together with the same base, we simply add the exponents together and keep the same base. Therefore .

 

The new expression becomes , however , therefore the expression becomes .

Example Question #1 : How To Solve For A Variable As Part Of A Fraction

\dpi{100} \small \frac{4 }{x} = \frac{2}{25}

Find x.

Possible Answers:

\dpi{100} \small \frac{8}{25}

\dpi{100} \small \frac{25}{8}

\dpi{100} \small 50

None

\dpi{100} \small 0.25

Correct answer:

\dpi{100} \small 50

Explanation:

Cross multiply:

\dpi{100} \small 4 \times 25 = 2x

\dpi{100} \small 100 = 2x

\dpi{100} \small x = 50

Example Question #2 : How To Solve For A Variable As Part Of A Fraction

The numerator of a fraction is the sum of 4 and 5 times the denominator. If you divide the fraction by 2, the numerator is 3 times the denominator. Find the simplified version of the fraction.

Possible Answers:

Correct answer:

Explanation:

Let numerator = N and denominator = D.

According to the first statement, 

N = (D x 5) + 4.

According to the second statement, N / 2 = 3 * D. 

Let's multiply the second equation by –2 and add itthe first equation:

–N = –6D

+[N = (D x 5) + 4]

=

–6D + (D x 5) + 4 = 0

–1D + 4 = 0

D = 4

Thus, N = 24.

Therefore, N/D = 24/4 = 6.

Example Question #1 : How To Solve For A Variable As Part Of A Fraction

If  , what is the value of ?

Possible Answers:

Correct answer:

Explanation:

Start by cross multiplying to get the equation

.

Then simplify by subtracting  from each side to get the solution,

 .

Example Question #472 : Algebra

If , then what is  equal to?

Possible Answers:

Correct answer:

Explanation:

We start by solving for x in  by multiplying 4 and 15, which gives us .

Then substituting 60 for x in,

 gives us

  which equals 0.

Example Question #1 : How To Solve For A Variable As Part Of A Fraction

If  , and , what is the value of ?

Possible Answers:

Correct answer:

Explanation:

Start by cross multiplying which gives us .

Simplify by dividing both sides by  which gives us .

Isolate  by dividing both sides by  and then adding  to both sides, which gives us .

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