November 2021 Paper 2 Q19
19
(a) \(\mathrm{f}(x) = (x + 2)^3\)
g is a function such that \(\quad \mathrm{gf}(x) = (x + 2)^{12}\)
Work out an expression for \(\ \mathrm{g}(x)\) [1 mark]
(b) \(\mathrm{h}(x) = x^2 + 5\)
k is a function such that \(\quad \mathrm{hk}(x) = 4x^2 + 5\)
Work out an expression for \(\ \mathrm{kh}(x)\) [2 marks]
| Answer | Mark | Comments |
|---|---|---|
| \(x^4\) | B1 |
| Answer | Mark | Comments |
|---|---|---|
| \(2x^2 + 10\) or \(2(x^2 + 5)\) | B2 | B1 \(\mathrm{k}(x) = 2x\) or \((\mathrm{k}(x))^2 = 4x^2\) or \(\mathrm{h}(2x) = 4x^2 + 5\) or \((2x)^2 + 5\) |
Additional guidance
| \(2(x^2 + 5)\) in working with answer \(2x^2 + 5\) | B1 |