If `f: Q->Q` is given by `f(x)=x^2` , then find `f^(-1)(9)`

Explanation

`f(x) = x^2`

Replace f(x) by y,

`y = x^2`

`x = sqrty`

take x by `f^(-1)x` and `y` by `x`.

`f-1x = sqrtx`
`
f-1(9) = sqrt9`
`
= ± 3`