Higher June 2017 Paper 4 Q18
18
(a) Solve by factorisation.\[2x^2 + 5x - 12 = 0\]
[3]
(b) Solve this equation.
Give each value correct to 2 decimal places.\[3x^2 + 2x - 3 = 0\]
Give each value correct to 2 decimal places.\[3x^2 + 2x - 3 = 0\]
[3]
| Answer | Marks | Part marks and guidance | |
|---|---|---|---|
| \((2x - 3)(x + 4)\) oe | 2 | M1 for any two factors that give two correct terms when expanded | If they use another method then award B1 for both answers correct. |
| 1.5 oe and −4 | 1 | Correct or FT their two factors | |
| Answer | Marks | Part marks and guidance | |
|---|---|---|---|
| [0].72 −1.39 | 3 | M2 for one correct answer or \(\dfrac{-2 \pm \sqrt{2^2 - 4 \times 3 \times -3}}{2 \times 3}\) or better or M1 for this formula with at most two errors if 0 scored allow SC1 for answers [0].720… or [0].721 and −1.38….. | for completing the square M1 for \(\left(x + \frac{1}{3}\right)^2 - \frac{10}{9}\) M1 for \(\sqrt{\frac{10}{9}} - \frac{1}{3}\) |