Higher June 2023 Paper 2 Q18
18 Rearrange \(\quad y = \dfrac{x + 8}{x} \quad\) to make \(x\) the subject. [3 marks]
| Answer | Mark | Comments |
|---|---|---|
| \(xy = x + 8\) or \(y = 1 + \dfrac{8}{x}\) | M1 | oe equation with fraction eliminated or oe equation with single fraction split into two terms eg \(y \times x = x + 8\) or \(y = \dfrac{x}{x} + \dfrac{8}{x}\) |
| \(xy - x = 8\) or \(x(y - 1) = 8\) | M1dep | oe equation with \(x\) terms collected eg \(x - xy = -8\) |
| \(x = \dfrac{8}{y - 1}\) or \(x = \dfrac{-8}{1 - y}\) | A1 | oe equation with \(x\) the subject eg \(-\dfrac{8}{1 - y} = x\) |
Additional guidance
| Up to M2 may be awarded for correct work with no answer or incorrect answer, even if this is seen amongst multiple attempts | |
| Correct answer in working with answer repeated on answer line without \(x =\) eg \(x = \dfrac{8}{y - 1}\) seen in working with answer \(\dfrac{8}{y - 1}\) | M1M1A1 |
| Do not allow incorrect simplification after correct answer seen eg \(x = \dfrac{8}{y - 1} \qquad x = \dfrac{8}{y} - 8\) | M2A0 |
| \(xy - x - 8 = 0\) with no further correct working | M1M0 |