Higher January 2019 Paper 2 Q9
9 Solve the simultaneous equations
\(4x + 5y = 4\)
\(2x - y = 9\)
Show clear algebraic working.
(3)
| Scheme | Marks |
|---|---|
| e.g. \(4x + 5y = 4\) \(4x - 2y = 18\) with the operation of subtraction \(4x + 5y = 4\) \(10x - 5y = 45\) With the operation of adding \(y = 2x - 9\) and \(4x + 5(2x - 9) = 4\) | M1 |
| M1 | |
| \(x = 3.5\) oe, \(y = -2\) | A1 |
| (3) | |
| (3 marks) |
Notes
M1: for correct method to eliminate one variable – multiplying one or both equations so the coefficient of \(x\) or \(y\) is the same in both with the intention to add or subtract to eliminate one variable (condone one arithmetic error) or isolating \(x\) or \(y\) in one equation and substituting into the other equation
M1: (dep) for substitution of found variable into one equation or correct method to eliminate second variable
A1: Dep on M1