1MA0 Higher November 2012 Paper 1 Q22
22 Solve the simultaneous equations
\[\begin{aligned} 3x + 2y &= 4 \\ 4x + 5y &= 17 \end{aligned}\](4)
| Working | Answer | Mark | Notes |
|---|---|---|---|
| \(12x + 8y = 16\) \(12x + 15y = 51\) \(7y = 35\) \(3x + 2 \times 5 = 4\) Alternative method \(x = \dfrac{4 - 2y}{3}\) \(4\left(\dfrac{4 - 2y}{3}\right) + 5y = 17\) \(16 - 8y + 15y = 51\) \(7y = 35\) \(x = \dfrac{4 - 2 \times 5}{3}\) | \(x = -2\) \(y = 5\) | 4 | M1 for a correct process to eliminate either \(x\) or \(y\) or leading to substitution (condone one arithmetic error) A1 for either \(x = -2\) or \(y = 5\) M1 (dep) for correct substitution of their found value A1 cao SC If M0 scored B1 for \(y = -2\) and \(x = 5\) |
Notes
(corrected from the printed mark scheme: the working line \(3x + 2 \times 5 = 4\) is printed as \(3x + 2 \times 5 = 6\))