Question 1012245
The function f(x)=9x+4 is one-to-one
rewrite as
y = 9x + 4
solve for x
9x = y - 4
x = (y - 4) / 9
exchange the x's and y's
y = (x - 4) / 9, therefore
f^-1(x) = (x - 4) / 9