The problem is as follows: Differentiate Y = 5^(-1/x)

My solution:

since d/dx(a^x) = a^x * ln(a)

I got dy/dx to be 5^(-1/x)ln5.

this is incorrect, the answer should be [5^(-1/x)ln5] / x^2

Thus, my question is where does that x ^ 2 denominator come from?