Higher November 2018 Paper 3 Q26
26 \(\text{f}(x) = \dfrac{2x + 3}{x - 4}\)
Work out \(\quad \text{f}^{-1}(x)\) [4 marks]
| Answer | Mark | Comments |
|---|---|---|
| \(y(x - 4) = 2x + 3\) | M1 | \(x(y - 4) = 2y + 3\) |
| \(yx - 4y = 2x + 3\) | M1dep | \(xy - 4x = 2y + 3\) |
| \(yx - 2x = 4y + 3\) or \(x(y - 2) = 4y + 3\) or \(x = \dfrac{4y + 3}{y - 2}\) | M1dep | \(xy - 2y = 4x + 3\) or \(y(x - 2) = 4x + 3\) |
| \(\dfrac{4x + 3}{x - 2}\) | A1 | oe Must be in terms of \(x\) |
Additional guidance
Ignore any attempt to give the domain of \(\text{f}^{-1}\)