Find whether `f(x) =(3x-4)/(x^2+1)` is one - one?

Explanation

Domain of `f(x)` is whole of `R`.
`y = (3x-4)/ (x^2+1) implies yx^2 − 3x + y + 4 = 0` which is a quadratic in x if `y ne 0`.
Thus giving two real values of x if `9 − 4y(y + 4) gt 0` if `y in (−9/2, 1/2)`
`:. f` is not one−one.