Anyway, to find the inverse of a function f(x) use the following steps:
1) Set y = f(x)
2) Now let x = f(y) (This amounts to reflecting the graph over the line y = x, which graphically gives the inverse function.)
3) Solve for y. We'll have y = g(x) as the solution. g(x) is the inverse to f(x).
In this case:
1) Let y = f(x) = 7x
2) Let x = 7y
3) y = (1/7)x <-- This is the inverse function, .
To prove this we need to show that