Question

Find the inverse function of f informally.verify that f(f-1(x))=x and f-1(f(x))=x

Answer 1

Hello : 
f(x) = 3x   f-1(x) = x/3
f(f-1(x)) = f(x/3) = 3(x/3) = x
f-1(f(x)) = f-1(3x= 3x/3=x