ACT Math Test : Exponents & Roots

Study concepts, example questions & explanations for ACT Math Test

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Example Questions

Example Question #4 : Fundamental Properties Of Roots & Exponents

 can be expressed as:

Possible Answers:

Correct answer:

Explanation:

It is important to be able to convert between root notation and exponent notation. The third root of a number (for example,  is the same thing as taking that number to the one-third power .

 

So when you see that you're taking the third root of , you can read that as  to the  power: 

 

This then allows you to apply the rule that when you take one exponent to another power, you multiply the powers:

 

This then means that you can express this as:

Example Question #31 : Exponents & Roots

 can be expressed as:

Possible Answers:

Correct answer:

Explanation:

With roots, it is important that you are comfortable with factoring and with expressing roots as fractional exponents. A square root, for example, can be expressed as taking that base to the  power. Using that rule, the given expression, , could be expressed using fractional exponents as:

 

This would allow you to then add the exponents and arrive at:

Since that 2 in the denominator of the exponent translates to "square root," you would have the square root of 

 

If you were, instead, to work backward from the answer choices, you would see that answer choice  factors to the given expression. If you start with:

 

You can express that as:

 

That in turn will factor to:

 

The first root then simplifies to , leaving you with: 

 

Therefore, as you can see, choice  factors directly back to the given expression.

Example Question #31 : Exponents & Roots

Which of the following is equal to  for all positive values of ?

Possible Answers:

Correct answer:

Explanation:

Simplify each of the expressions to determine which satisfies the condition of the problem:

 

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