4400 Higher June 2010 Paper 4 Q13
13
(a) Solve \(x^2 - 8x + 12 = 0\) (3)
(b) Solve the simultaneous equations \[\begin{aligned} y &= 2x \\ 4x - 5y &= 9 \end{aligned}\] (3)
| Scheme | Marks |
|---|---|
| \((x - 6)(x - 2)\ (= 0)\) or \(\dfrac{8 \pm \sqrt{64 - 48}}{2}\) | M2 |
| \(x = 6\) or 2 | A1 |
| (3) |
Notes
M2: M1 for 1 correct factor or \((x + 6)(x + 2)\)
or \(\dfrac{8 \pm \sqrt{-8^2 - 4 \times 12}}{2}\) condone one sign error
A1: Ans only = M0M0A0 Answer depended on M2 achieved
| Scheme | Marks |
|---|---|
| \(4x - 10x = 9\) or \(2y - 5y = 9\) oe \(-6x = 9\) or \(-3y = 9\) | M1 |
| −1.5, −3 | A1 A1 |
| (3) | |
| (6 marks) |
Notes
M1: correct sub/elimin to get 1 eqn 1 unknown
A1 A1: Ans only = M0A0A0