Higher November 2019 Paper 1 Q23
23
(a) Factorise \(\quad 5x^2 + 6x - 8\) [2 marks]
(b) Simplify fully \(\quad \dfrac{x^2 + 9x + 14}{x^2 - 4}\) [3 marks]
| Answer | Mark | Comments |
|---|---|---|
| \((5x - 4)(x + 2)\) | B2 | brackets in either order B1 factorisation to \((5x + a)(x + b)\) where \(ab = -8\) or \(a + 5b = 6\) or \(\dfrac{1}{5}(5x - 4)(5x + 10)\) |
Additional guidance
| Ignore any attempt to solve \((5x - 4)(x + 2) = 0\) | |
| Attempt at further factorisation, eg \((5x - 4)(x + 2) = 5(x - 0.8)(x + 2)\) | B1 |
| Answer | Mark | Comments |
|---|---|---|
| \((x + 2)(x + 7)\) | M1 | brackets in either order |
| \((x + 2)(x - 2)\) | M1 | brackets in either order |
| \(\dfrac{x + 7}{x - 2}\) | A1 |
Additional guidance
| Further cancelling, eg \(\dfrac{x + 7}{x - 2} = \dfrac{7}{2}\) | M1M1A0 |