Find a formula for the inverse of the function

Question

f(x) = e^7x-9

Answer 1

Let y = f(x).  So, y = e^7x-9

 

Switch x and y to get x = e^7y-9

 

Solve for y:  lnx = ln(e^7y-9)

 

                   lnx = 7y-9

 

So, y = ( lnx + 9 )/7

 

f^-1(x) = (lnx + 9)/7