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
Answer is: c
a. x
b. x - 6
c. x - 3
d. 2x + 3
e. 2x + 6
Answer is: c
5^x - 5^(x-3)
= 5^(x-3) (5^3 - 1) - take out common values
= 5^(x-3) (125-1)
=124*5^(x-3) = 124*5^y
so y = x-3
