GRE Math : Exponents

Study concepts, example questions & explanations for GRE Math

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Example Questions

Example Question #82 : Exponents

If , what is the value of ?

Possible Answers:

Correct answer:

Explanation:

Rewrite the term on the left as a product. Remember that negative exponents shift their position in a fraction (denominator to numerator).

The term on the right can be rewritten, as 27 is equal to 3 to the third power.

Exponent rules dictate that multiplying terms allows us to add their exponents, while one term raised to another allows us to multiply exponents.

We now know that the exponents must be equal, and can solve for .

 

Example Question #1 : How To Add Exponents

If , what is the value of ?

Possible Answers:

Correct answer:

Explanation:

Since the base is 5 for each term, we can say 2 + n =12.  Solve the equation for n by subtracting 2 from both sides to get n = 10.

Example Question #53 : Exponents

Simplify .

Possible Answers:

Correct answer:

Explanation:

Start by simplifying each individual term between the plus signs. We can add the exponents in  and  so each of those terms becomes . Then multiply the exponents in  so that term also becomes . Thus, we have simplified the expression to  which is .

Example Question #2 : How To Add Exponents

Simplify .

Possible Answers:

Correct answer:

Explanation:

First, simplify  by adding the exponents to get .

Then simplify  by multiplying the exponents to get .

This gives us . We cannot simplify any further.

Example Question #1551 : Gre Quantitative Reasoning

If , what is the value of 

Possible Answers:

Correct answer:

Explanation:

To attempt this problem, note that .

Now note that when multiplying numbers, if the base is the same, we may add the exponents:

This can in turn be written in terms of nine as follows (recall above)

Example Question #3 : How To Add Exponents

If , what is the value of 

Possible Answers:

Correct answer:

Explanation:

When dealing with exponenents, when multiplying two like bases together, add their exponents:

However, when an exponent appears outside of a parenthesis, or if the entire number itself is being raised by a power, multiply:

Example Question #751 : Algebra

Simplify: 32 * (423 - 421)

Possible Answers:

4^4

None of the other answers

3^21

3^3 * 4^21 * 5

3^3 * 4^21

Correct answer:

3^3 * 4^21 * 5

Explanation:

Begin by noting that the group (423 - 421) has a common factor, namely 421.  You can treat this like any other constant or variable and factor it out.  That would give you: 421(42 - 1). Therefore, we know that:

32 * (423 - 421) = 32 * 421(42 - 1)

Now, 42 - 1 = 16 - 1 = 15 = 5 * 3.  Replace that in the original:

32 * 421(42 - 1) = 32 * 421(3 * 5)

Combining multiples withe same base, you get:

33 * 421 * 5

Example Question #461 : Algebra

Quantitative Comparison

Quantity A: 64 – 32

Quantity B: 52 – 42

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:

Quantity A is greater.

Explanation:

We can solve this without actually doing the math. Let's look at 64 vs 52. 64 is clearly bigger. Now let's look at 32 vs 42. 32 is clearly smaller. Then, bigger – smaller is greater than smaller – bigger, so Quantity A is bigger.

Example Question #1561 : Gre Quantitative Reasoning

, and  is odd.

Quantity A: 

Quantity B: 

 

Possible Answers:

Quantity B is greater.

The relationship cannot be determined from the information given.

The two quantities are equal.

Quantity A is greater.

Correct answer:

Quantity A is greater.

Explanation:

The first thing to note is the relationship between (–b) and (1 – b):

 (–b) < (1 – b) because (–b) + 1 = (1 – b).

Now when b > 1, (1 – b) < 0 and –b < 0. Therefore (–b) < (1 – b) < 0.

Raising a negative number to an odd power produces another negative number.

Thus (–b)a < (1 – b)a < 0.

Example Question #22 : How To Multiply Exponents

(b * b* b7)1/2/(b3 * bx) = b5  

If b is not negative then x = ?

Possible Answers:

–1

7

–2

1

Correct answer:

–2

Explanation:

Simplifying the equation gives b6/(b3+x) = b5.  

In order to satisfy this case, x must be equal to –2.

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