BTGModeratorVI wrote: ↑Sat May 16, 2020 7:29 am
What is the value of (10^x)(10^y)?
(1) 2^(x+y) = 16
(2) 5^(x+y) = 625
Answer:
D
Source: Official guide
Target question: What is the value of [m]10^x10^y[/m]?
This is a good candidate for
rephrasing the target question.
Useful property: (x^a)(x^b)=x^(a+b)
So, we can take
(10^x)(10^y) and rewrite it as
10^(x+y)
In order to evaluate
10^(x+y), we must find the value of
x+y
REPHRASED target question: What is the value of x+y?
Aside: Here’s a video with tips on rephrasing the target question: https://www.gmatprepnow.com/module/gmat- ... cy?id=1100
Statement 1: 2^(x+y)=16
We can rewrite the right side as follows: 2^(x+y)=2^4, which means it must be the case that
x+y=4
Since we can answer the
REPHRASED target question with certainty, statement 1 is SUFFICIENT
Statement 2: 5^(x+y)=625
We can rewrite the right side as follows: 5^(x+y)=5^4, which means it must be the case that
x+y=4
Since we can answer the
REPHRASED target question with certainty, statement 2 is SUFFICIENT
Answer: D
Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
