posted by Janie on .
if f(x) = (x/7)-3 find f^-1(x)
I'm completely lost! Help
The inverse function f^-1(x) gives you back x when you input y = f(x) as the independent variable.
Start with y = (x/7)-3
y + 3 = x/7
x = 7y + 21
Since you are using x as the independent variable of the inverse function, you have to switch x and y in the equation above.
The inverse function is therefore
f^-1(x) = 7x + 21
Check: Use (7x +21) as "x" in the f(x) equation, and you get x back.