Find the function \(g(t)\) if \(f(t)=3 t-2\) and \((g \circ f)^{-1}(t)=t-2\).

Find the function \(g(t)\) if \(f(t)=3 t-2\) and \((g \circ f)^{-1}(t)=t-2\).
  1. \(g(t)=\frac{(t-8)}{3}\)
  2. \(g(t)=\frac{(t+8)}{3}\)
  3. \(g(t)=\frac{(8-t)}{3}\)
  4. \(g(t)=3 t-8\)

Solution

Given, \((g \circ f)^{-1}(t)=t-2\) \(\begin{aligned} & \Rightarrow \quad(g \circ f)(t)=t+2 \\ & \Rightarrow \quad g(f(t))=t+2 \\ & \Rightarrow \quad g(3 t-2)=(t+2) \quad\{\because f(t)=3 t-2\} \\ \end{aligned}\) Now replace \(t\) by \(\frac{t}{3}\), we get \(g(t-2)=\left(\frac{t}{3}+2\right)\) Again replace \(t\) by \(t+2\), we get \(g(t)=\frac{t+2}{3}+2=\frac{t+8}{3}\)

Asked in: AP EAMCET 2020 (18 Sep Shift 1)

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