sandy wrote:

Which of the following is equal to \(\frac{2^x^-^y}{2^x^+^y}\) for all integers x and y ?

A. \(4^-^x\)

B. \(4^-^y\)

C. \(2^x^y\)

D. \(4^x\)

E. \(4^y\)

Another approach is to use the INPUT-OUTPUT method.

Let x = 2 and y = 1

In this case, \(\frac{2^x^-^y}{2^x^+^y}\) = \(\frac{2^1}{2^3}\) = \(\frac{1}{4}\)

So, when the INPUT is x = 2 and y = 1, the OUTPUT is 1/4

The correct answer choice will be the one that has an OUTPUT of 1/4 when the INPUT is x = 2 and y = 1

A. \(4^-^x\) = 4^(-2) = 1/16. ELIMINATE A.

B. \(4^-^y\) = 4^(-1) = 1/4. KEEP B.

C. \(2^x^y\) = 2^(2) = 4. ELIMINATE C.

D. \(4^x\) = 4^(2) = 16. ELIMINATE D.

E. \(4^y\) = 4^(1) = 4. ELIMINATE E.

RELATED RESOURCES (videos)- Variables in the Answer Choices -

https://www.greenlighttestprep.com/modu ... /video/936- Tips for the Algebraic Approach -

https://www.greenlighttestprep.com/modu ... /video/937 - Tips for the Input-Output Approach -

https://www.greenlighttestprep.com/modu ... /video/938 Cheers,

Brent

_________________

Brent Hanneson – Creator of greenlighttestprep.com

Sign up for my free GRE Question of the Day emails