4MA0 Foundation June 2017 Paper 2R Q21
21 Solve the simultaneous equations.
\[\begin{aligned} 5x - 2y &= 9.5 \\ 4x + 2y &= 13 \end{aligned}\]Show clear algebraic working.
(3)
| Scheme | Marks |
|---|---|
Eg \(9x = 22.5\) or \(18y = 27\) or \(-18y = -27\) or \(5x - (13 - 4x) = 9.5\) or \(4x + 5x - 9.5 = 13\) or \(5\left(\dfrac{13 - 2y}{4}\right) - 2y = 9.5\) or \(4\left(\dfrac{9.5 + 2y}{5}\right) + 2y = 13\) | M1 |
| Eg \(5 \times \text{"}2.5\text{"} - 2y = 9.5\) or \(5x - 2 \times \text{"}1.5\text{"} = 9.5\) | M1 |
| \(x = 2.5,\ y = 1.5\) | A1 |
| (3) | |
| (3 marks) |
Notes
M1: For a complete method to eliminate one variable (condone one arithmetic error)
M1: Dep on M1
For substituting the other variable or starting again to eliminate the other variable
A1: dep on M1
NB: candidates showing no correct working score 0 marks.