If 5^x – 5^x - 3 = (124)(5^y), what is y in terms of x?
A. x
B. x - 6
C. x - 3
D. 2x + 3
E. 2x + 6
Please help...how do I approach these types of questions? Thanks.
what is y in terms of x?
This topic has expert replies
-
- Master | Next Rank: 500 Posts
- Posts: 178
- Joined: Wed May 14, 2008 3:51 pm
- Thanked: 16 times
- Followed by:1 members
- GMAT Score:99%+
First of all i think you made a mistake with the question..
I think it should be 5^x – 5^(x - 3) = (124)(5^y) If it isn't this.. it doesn't make sense.
Answer is C.
5^x – 5^(x - 3) = (124)(5^y)
5^x = 5^3 * 5^(x-3)
So:
5^(x-3)*5^3 – 5^(x - 3) = (124)(5^y)
5^(x-3)(5^3 - 1) = (124)(5^y)
5^(x-3)(124) = (124)(5^y)
Therefore:
5^(x-3) = 5^y
so y = x-3
I think it should be 5^x – 5^(x - 3) = (124)(5^y) If it isn't this.. it doesn't make sense.
Answer is C.
5^x – 5^(x - 3) = (124)(5^y)
5^x = 5^3 * 5^(x-3)
So:
5^(x-3)*5^3 – 5^(x - 3) = (124)(5^y)
5^(x-3)(5^3 - 1) = (124)(5^y)
5^(x-3)(124) = (124)(5^y)
Therefore:
5^(x-3) = 5^y
so y = x-3