Higher June 2018 Paper 2R Q20
20 Solve the inequality \(4x^2 - 5x - 6 \gt 0\)
(4)
| Scheme | Marks |
|---|---|
| eg \((4x + 3)(x - 2)\) or (\(x\) =) \(\dfrac{-(-5) \pm \sqrt{(-5)^2 - 4 \times 4 \times (-6)}}{2 \times 4}\) | M1 |
| (\(x\) =) \(-\dfrac{3}{4}\) and 2 | A1 |
| M1 | |
| \(x \lt -\dfrac{3}{4}\), \(x \gt 2\) | A1 |
| (4) | |
| (4 marks) |
Notes
M1: first step to finding the critical values
A1: for two correct critical values
M1: (dep on two critical values having been found) for a diagram showing the inequalities OR \(x \lt a\) and \(x \gt b\) where \(a\) is their lower critical value and \(b\) is their upper critical value OR \(x \gt 2\) OR \(x \lt \dfrac{-3}{4}\) OR \(\dfrac{-3}{4} \gt x \gt 2\)
A1: for both correct inequalities