Question

Find the inverse of the function
f (x) = 15 + sqrt 5x - 5

Answer 1

`15 + √(5x - 5) = f(x)`

Replace y for x and vice versa

`15 + √(5y - 5) = x`

Solve for y.

`15 + 5y - 5 = {x}^(2)`

`15 + 5y = {x}^(2) + 5`

`5y = {x}^(2) - 10`

`y = \frac{ {x}^(2) - 10 }{5}`

`f {}^( - 1) (x) = \frac{ {x}^(2) - 10 }{5}`

If