4400 Higher June 2004 Paper 3 Q19
19
\[\mathrm{f} : x \mapsto 2x - 1\] \[\mathrm{g} : x \mapsto \frac{3}{x},\ x \neq 0\](a) Find the value of
(i) \(\mathrm{f}(3)\),
(ii) \(\mathrm{fg}(6)\). (2)
(b) Express the inverse function \(\mathrm{f}^{-1}\) in the form \(\mathrm{f}^{-1} : x \mapsto\) ... (2)
(c)
(i) Express the composite function \(\mathrm{gf}\) in the form \(\mathrm{gf} : x \mapsto\) ...
(ii) Which value of \(x\) must be excluded from the domain of \(\mathrm{gf}\)? (2)
| Scheme | Marks |
|---|---|
| (i) Answer: 5 | B1 |
| (ii) Answer: 0 | B1 |
| (2) |
Notes
B1: cao
B1: cao
| Scheme | Marks |
|---|---|
| eg \(\begin{matrix} \times 2 \to -1 \\ \div 2 \leftarrow +1 \end{matrix}\) or attempt to make \(x\) the subject of \(y = 2x - 1\) | M1 |
| \(\dfrac{x + 1}{2}\) oe | A1 |
| (2) |
| Scheme | Marks |
|---|---|
(i) Answer: \(\dfrac{3}{2x - 1}\) | B1 |
| (ii) Answer: \(\frac{1}{2}\) | B1 |
| (2) | |
| (6 marks) |