Posted by Janie on .
if f(x) = (x/7)3 find f^1(x)
I'm completely lost! Help

CONFUSED~MATH 
drwls,
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.