Question

If f(x) =5x-25 and g(x) = (1/5)X+5, which expression could be used to verify g(x) is the inverse of f(x)

Answer 1

Answer:
f(g(x)) = x

Explanation:
In order to prove that one function is the inverse of the other, all you have to do is substitute in the main function with the inverse one and solve. If the result is x, then it is verified that one function is the inverse of the other. 
Now for the given functions we have:
f(x) =5x-25
g(x) = (1/5)x+5
We want to prove that g(x) is the inverse of f(x).
Substitute in the above formula and compute the result as follows:
f(g(x)) = 5((1/5)x+5) - 25
          = x + 25 - 25
          = x
The final result is "x", therefore, it is verified that g(x) is the inverse of f(x)

Hope this helps :)

Answer 2

If g(x) is the inverse of f(x) the  f(g(x)) = x

f(g(x)) =  5 ( 1/5x + 5) - 25 

if you simplify this you'll get x  so it is the inverse.