Question

If f(x) = 5x, what is f–1(x)?

Answer 1

We are given f(x) = 5x
and we are to find inverse of f(x).

Step 1:
Replace f(x) by y.
So,

y = 5x

Step 2:
Isolate x
So,

x = y/5

Step 3:
Replace x by f'(y)
So,

f'(y) = y/5

Step 4:
Replace all occurrences of y by x.
So,

f'(x) = x/5

Therefore, the inverse of f(x) = 5x is f'(x) = x/5