Mathematics 9709 · AS & A Level · Functions

Functions — practice question

The functions $f$ and $g$ are given for $x \in \mathbb{R}$ by $f: x \mapsto \frac{1}{2}x - a$ and $g: x \mapsto 3x + b$, with $a$ and $b$ constant.
(a)[4]

Since $g g(2) = 10$ and $f^{-1}(2) = 14$, find the values of $a$ and $b$.

(b)[2]

Using these values of $a$ and $b$, find an expression for $g f(x)$ in the form $cx + d$, where $c$ and $d$ are constants.

Worked solution & mark scheme

This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: The correct equation is $3(3x+b)+b=9x+4b$

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