Question

Given a function If as f(x) = 5x + 4, x ∈ R. If g : R → R is inverse of function ‘f then

Options

• `"g"("x") = 4"x" + 5`

• `"g"("x") = 5/(4"x" - 5)`

• `"g"("x") = ("x" - 4)/5`

• `"g"("x") = 5"x" - 4`

Answer 1

`"g"("x") = ("x" - 4)/5`

Explanation:

as `"y" = "f"("x")`

`=> "y" = 5"x" + 4`

`=> "x" = ("y" - 4)/5`

`therefore "f"^-1 ("y") = ("y" - 4)/5`

or `"f"^-1 ("x") = ("x" - 4)/5`