How to add exponents - ACT Math

Card 0 of 17

Question

Simplify: hn + h–2n

Answer

h–2n = 1/h2n

hn + h–2n = hn + 1/h2n

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Question

For all x, 2_x_2 times 12_x_3 equals...

Answer

You multiply the integers, then add the exponents on the x's, giving you 24_x_5.

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Question

Multiply: 2_x_² * 3x

Answer

When multiplying exponents you smiply add the exponents.

For 2_x_² times 3_x_, 2 times 3 is 6, and 2 + 1 is 3, so 2_x_² times 3_x_ = 6_x_3

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Question

What is 23 + 22 ?

Answer

Using the rules of exponents, 23 + 22 = 8 + 4 = 12

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Question

Solve for where:

Answer

The only value of x where the two equations equal each other is 1. All you have to do is substitute the answer choices in for x.

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Question

If , what is the value of ?

Answer

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.

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Question

Simplify: y3x4(yx3 + y2x2 + y15 + x22)

Answer

When you multiply exponents, you add the common bases:

y4 x7 + y5x6 + y18x4 + y3x26

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Question

A particle travels 9 x 107 meters per second in a straight line for 12 x 10-6 seconds. How many meters has it traveled?

Answer

Multiplying the two numbers yields 1080. Expressed in scientific notation 1080 is 1.08 x 103.

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Question

Simplify the following:

Answer

When common variables have exponents that are multiplied, their exponents are added. So _K_3 * _K_4 =K(3+4) = _K_7. And _M_6 * _M_2 = M(6+2) = _M_8. So the answer is _K_7/_M_8.

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Question

Simplify: 3y2 + 7y2 + 9y3 – y3 + y

Answer

Add the coefficients of similar variables (y, y2, 9y3)

3y2 + 7y2 + 9y3 – y3 + y =

(3 + 7)y2 + (9 – 1)y3 + y =

10y2 + 8y3 + y

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Question

If , what is the value of ?

Answer

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 .

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Question

Solve for :

Answer

First, reduce all values to a common base using properties of exponents.

Plugging back into the equation-

Using the formula

We can reduce our equation to

So,

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Question

Which expression is equivalent to the following?

Answer

The rule for adding exponents is . We can thus see that and are no more compatible for addition than and are.

You could combine the first two terms into , but note that PEMDAS prevents us from equating this to (the exponent must solve before the distribution).

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Question

Express as a power of 2:

Answer

Since the problem requires us to finish in a power of 2, it's easiest to begin by reducing all terms to powers of 2. Fortunately, we do not need to use logarithms to do so here.

Thus,

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Question

Simplify the following

.

Answer

Begin by performing the last group's multiplication:

Now, remember that you treat variables and their powers as similar terms to be combined. Therefore, you can combine the and terms, giving you:

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Question

Simplify the following expression:

Answer

When multiplying bases that have exponents, simply add the exponents. Note that you can only add the exponents if the bases are the same. Thus:

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Question

Simplify the following:

Answer

When multiplying two exponential expressions with the same bases, add the exponents. In this problem, the answer turns out to be .

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