# Thread: Variables in the Exponent

1. ## Variables in the Exponent

Given: $5^x+2^y = 2^x+5^y = \frac{7}{10}$

Find: $(x+y)^{-1}$

We've been covering exponential functions pretty extensively, but I don't have a clue how to start this problem.

2. Originally Posted by fizz
Given: $5^x+2^y = 2^x+5^y = \frac{7}{10}$

Find: $(x+y)^{-1}$

We've been covering exponential functions pretty extensively, but I don't have a clue how to start this problem.
Notice that $\frac{7}{10}=2^{-1}+5^{-1}$.