How to subtract exponents

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SAT Math › How to subtract exponents

Questions 1 - 10
1

Simplify:

Explanation

Although we have different bases, we know that .

Therefore,

.

Finally, we factor out to get

.

2

Evaluate

Explanation

When subtracting exponents, we don't multiply the exponents but we try to factor to see if we simplify the subtraction problem. In this case, we can simplify it by factoring . We get .

3

Evaluate

Explanation

Although we have different bases, we know that . As long as exponents are the same, you are allowed to break the base to its prime numbers. Next, we can factor .

4

Simplify: 32 * (423 - 421)

4^4

3^21

3^3 * 4^21

3^3 * 4^21 * 5

None of the other answers

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

5

If m and n are integers such that m < n < 0 and _m_2 – _n_2 = 7, which of the following can be the value of m + n?

I. –5

II. –7

III. –9

I only

II only

I and II only

II and III only

I, II and III only

Explanation

m and n are both less than zero and thus negative integers, giving us _m_2 and _n_2 as perfect squares. The only perfect squares with a difference of 7 is 16 – 9, therefore m = –4 and n = –3.

6

Evaluate:

Explanation

When subtracting with exponents, we try to factor out some terms.

We can factor out to get

.

7

Simplify so that all exponents are positive:

Explanation

When we divide two polynomials with exponents, we subtract their exponents.

Remember that the question asks that all exponents be positive numbers. Therefore:

8

Explanation

To simplify, we can rewrite the numerator using a common exponential base.

Now, we can factor out the numerator.

The eights cancel to give us our final answer.

9

Solve:

Explanation

Subtract the denominator exponent from the numerator's exponent, since they have the same base.

10

Simplify the following expression:

Explanation

The correct answer can be found by subtracting exponents that have the same base. Whenever exponents with the same base are divided, you can subtract the exponent of the denominator from the exponent of the numerator as shown below to obtain the final answer:

You do not do anything with the y exponent because it has no identical bases.

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