Higher November 2020 Unit 2 Q13
13.
(a) Factorise \(4x^2 - 81\). [2]
(b) Factorise \(7x^2 + 10x - 8\). [2]
(c) Factorise \((x + 2)^3 + 5(x + 2)^2\). [2]
| Scheme | Marks | Comments |
|---|---|---|
| \((2x + 9)(2x - 9)\) | B2 | B1 for \((2x \ldots 9)(2x \ldots 9)\) |
| Scheme | Marks | Comments |
|---|---|---|
| \((7x - 4)(x + 2)\) | B2 | B1 for \((7x \ldots 4)(x \ldots 2)\) |
| Scheme | Marks | Comments |
|---|---|---|
| \((x + 2)^2(x + 7)\) OR \((x + 2)(x + 2)(x + 7)\) | B2 | B1 for \((x + 2)^2(x + 2 + 5)\) OR \((x + 2)[(x + 2)^2 + 5(x + 2)]\) OR \((x + 7)(x^2 + 4x + 4)\) OR \((x + 2)(x^2 + 9x + 14)\). Allow B1 for \((x + 2)^2(x + k)\) where \(k \ne 0\), 2 or 7. |