ACT Math : How to find a ratio of exponents

Study concepts, example questions & explanations for ACT Math

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Example Questions

Example Question #1 :How To Find A Ratio Of Exponents

Ifand, then which of the following CANNOT be the value of?

Possible Answers:

Correct answer:

Explanation:

Even roots of numbers can either be positive or negative. Thus, x = +/- 5 and y = +/- 3. The possible values from x + y can therefore be:

(-5) + (-3) = -8

(-5) + 3 = -2

5 + (-3) = 2

5 + 3 = 8

Example Question #1 :How To Find A Ratio Of Exponents

Iffor all\ dpi {100} \ nnot equal to 0, which of the following must be true?

Possible Answers:

\dpi{100} \small y+x = 6

\dpi{100} \small \frac{y}{x} = 6

\dpi{100} \small yx = 6

\dpi{100} \small \frac{x}{y} = 6

\dpi{100} \small y-x = 6

Correct answer:

\dpi{100} \small y-x = 6

Explanation:

Remember that\dpi{100} \small \frac{n^{y}}{n^{x}}=n^{y-x}

Since the problem states that, you can assume that\ dpi {100} \ n^{y-x}=n^{6}

This shows that\dpi{100} \small y-x = 6.

Example Question #1 :Exponential Ratios

Ifandare positive integers and, then what is the value of?

Possible Answers:

Correct answer:

Explanation:

43= 64

Alternatively written, this is 4(4)(4) = 64 or 43= 641.

Thus,m= 3 andn= 1.

m/n= 3/1 = 3.

Example Question #811 :Algebra

Write the following logarithm in expanded form:

Possible Answers:

Correct answer:

Explanation:

Example Question #812 :Algebra

Ifandare both rational numbers and, what is?

Possible Answers:

Correct answer:

Explanation:

This question is asking you for the ratio of m to n. To figure it out, the easiest way is to figure out when 4 to an exponent equals 8 to an exponent. The easiest way to do that is to list the first few results of 4 to an exponent and 8 to an exponent and check to see if any match up, before resorting to more drastic means of finding a formula.

And, would you look at that.. Therefore,.

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