Question

If f : R → R defined by f(x) = 3x − 4 is invertible, then write f⁻¹ (x).

Answer 1

$$\begin{gathered} \text{Let}{f}^{-1}\left(x\right)=y...\left(1\right) \\ \Rightarrow f\left(y\right)=x \\ \Rightarrow 3y-4=x \\ \Rightarrow 3y=x+4 \\ \Rightarrow y=\frac{x+4}{3} \\ \Rightarrow f^{-1}\left(x\right)=\frac{x+4}{3}[\text{from}\left(1\right)\text{]} \end{gathered}$$