June 2016 Paper 1 Q18
18 Factorise fully \(\qquad x^4 - 81\) [2 marks]
| Answer | Mark | Comments |
|---|---|---|
| \((x^2 - 9)(x^2 + 9)\) or \((x + 3)(x^3 - 3x^2 + 9x - 27)\) or \((x - 3)(x^3 + 3x^2 + 9x + 27)\) | M1 | |
| \((x + 3)(x - 3)(x^2 + 9)\) | A1 | Do not award A1 if further working |