4MA0 Foundation January 2017 Paper 1R Q20
20
(a) Solve \[\begin{aligned} 7x + 2y &= 16 \\ 5x - 2y &= 20 \end{aligned}\] Show clear algebraic working. (3)
(b) Expand and simplify \((k + 9)(k - 5)\) (2)
| Scheme | Marks |
|---|---|
| \(12x = 36\) | M1 |
| e.g. \(7 \times \text{"}3\text{"} + 2y = 16\) | M1 |
| \(x = 3\) oe, \(y = -2.5\) | A1 |
| (3) |
Notes
M1: for addition of given equations or a complete method to eliminate \(y\) (condone one arithmetic error)
M1: (dep) for method to find second variable
A1: NB.
Candidates showing no working score 0 marks
| Scheme | Marks |
|---|---|
| \(k^2 + 9k - 5k - 45\) | M1 |
| \(k^2 + 4k - 45\) | A1 |
| (2) | |
| (5 marks) |
Notes
M1: for 3 correct or all 4 terms correct ignoring signs or
\(k^2 + 4k + \ldots\) (printed as \(y^2 + 4k + \ldots\)) or \(\ldots + 4k - 45\)