1MA0 Higher November 2013 Paper 1 Q15
15 Solve the simultaneous equations \[\begin{aligned} 3x + 4y &= 5 \\ 2x - 3y &= 9 \end{aligned}\] (4)
| Working | Answer | Mark | Notes |
|---|---|---|---|
| \(6x + 8y = 10\) \(6x - 9y = 27\) \(y = -1\) \(3x - 4 = 5\) \(3x = 9\) \(x = 3\) OR \(9x + 12y = 15\) \(8x - 12y = 36\) \(x = 3\) \(9 + 4y = 5\) \(4y = -4\) \(y = -1\) | \(x = 3\), \(y = -1\) | 4 | M1 for a correct process to eliminate either variable (condone one arithmetic error) A1 cao for either \(x\) or \(y\) M1 (dep on M1) for correct substitution of found value into one of the equations or appropriate method after starting again (condone one arithmetic error) A1 cao OR M1 for full method to rearrange and substitute to eliminate either variable (condone one arithmetic error) A1 cao for either \(x\) or \(y\) M1 (dep on M1) for correct substitution of found value into one of the equations or appropriate method after starting again (condone one arithmetic error) A1 cao Trial and improvement scores 0 marks unless both \(x\) and \(y\) are correct |