ACT Math : Algebra

Study concepts, example questions & explanations for ACT Math

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Example Questions

Example Question #1 : How To Subtract Exponents

Reduce  to simplest form.

Possible Answers:

Correct answer:

Explanation:

When dividing terms with the same bases but different exponents, you will need to subtract all the pertinent exponents.

 

 becomes ,

 becomes ,

and  stays the same because there is no other z term to combine with it.

Thus resulting in:

 

Example Question #1 : How To Subtract Exponents

Simplify: 32 * (423 - 421)

Possible Answers:

3^3 * 4^21

None of the other answers

3^3 * 4^21 * 5

3^21

4^4

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 #2 : How To Subtract Exponents

Simplify. Leave no negative exponents in the final answer.

 

Possible Answers:

None of these are the correct answer.

Correct answer:

Explanation:

The first step in the problem is to combine like terms in the numerator, remembering that :

Next, we resolve the numerator, using  and 

Lastly, simplify the negative exponent using 

 

 Thus,  

Example Question #1 : How To Subtract Exponents

Simplify to remove fractions:

Possible Answers:

None of these are correct.

Correct answer:

Explanation:

The first step is to simplify each fraction by dividing like terms, remembering that , to get: 

Next, combine using multiplication and the rule :

Since the problem specifies that we must avoid fractions, we will not eliminate the negative exponents.

So, 

Example Question #2 : How To Subtract Exponents

Simplify the following: 

Possible Answers:

Correct answer:

Explanation:

When dividing exponential expressions with the same base, subtract the exponents. In this problem, the exponents are  and . When subtracted, the result is . Thus, the correct answer is .

Example Question #1 : How To Subtract Exponents

 can be written as which of the following?

A.

B.

C.

Possible Answers:

A, B and C

B only

B and C

C only

A and C

Correct answer:

B and C

Explanation:

A is not equivalent because exponents in denominators mean subtraction of exponents and not division of them. Furthermore, A, when computed, comes out to instead of .

B is equivalent by the aforementioned exponential property, while C is simply computing the expression.

Example Question #1 : How To Subtract Exponents

Simplify: 

Possible Answers:

Correct answer:

Explanation:

When two exponents with the same base are being divided, subtract the exponent of the denominator from the exponent of the numerator to yield a new exponent. Attach that exponent to the base, and that is your answer. 

In this case, subtract  from . That yields  as the new exponent and  as the answer.

Example Question #1 : How To Divide Exponents

Simplify Actmath_45_508_q9

Possible Answers:

Actmath_45_508_q9_2

None of the answers are correct

Actmath_45_508_q9_4

Actmath_45_508_q9_5

Actmath_45_508_q9_3

Correct answer:

Actmath_45_508_q9_2

Explanation:

When working with polynomials, dividing is the same as multiplying by the reciprocal.  After multiplying, simplify.  The correct answer for division is

 Actmath_45_508_q9_2

and the correct answer for multiplication is

Actmath_45_508_q9_3

Example Question #1 : How To Divide Exponents

Simplify:

\small \frac{x^2y^3z^4}{x^3y^4z^2}

Possible Answers:

\small \frac{z}{x^2y^2}

\small \frac{z^2}{xy}

\small xyz^2

\small \frac{yz^2}{x}

Correct answer:

\small \frac{z^2}{xy}

Explanation:

To simply exponents in a fraction, subtract the exponent for each variable in the denominator from the exponent in the numerator. This will leave you with

\small x^{-1}y^{-1}z^2 or \small \frac{z^2}{xy}

Example Question #61 : Exponents

What is the value of m where:

 

Possible Answers:

1

2

4

-2

6

Correct answer:

2

Explanation:

If n=4, then 64(4/12)=64(1/3)=4.  Then, 4=mŸ4(1+m)/(m+4). If 2 is substituted for m, then 4=2Ÿ4(1+2)/(2+4)=2Ÿ41/2=2Ÿ√4=2Ÿ2=4.

 

 

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