November 2021 Paper 1 Q9
9 Expand and simplify fully \(\quad (2x - 5)(3x - 4)(x + 2)\) [3 marks]
| Answer | Mark | Comments |
|---|---|---|
| Expanding second and third bracket \(3x^2 + 6x - 4x - 8\) with at least three terms correct or \(3x^2 + 2x + k\) where \(k\) is a non-zero constant | M1 | oe expansion attempt of one pair of brackets eg1 first and second brackets \(6x^2 - 8x - 15x + 20\) with at least three terms correct or \(6x^2 - 23x + k\) where \(k\) is a non-zero constant eg2 first and third brackets \(2x^2 + 4x - 5x - 10\) with at least three terms correct or \((2x^2 - x + k)\) where \(k\) is a non-zero constant |
| \(6x^3 + 12x^2 - 8x^2 - 16x\) or \(6x^3 + 4x^2 - 16x\) or \(-15x^2 - 30x + 20x + 40\) or \(-15x^2 - 10x + 40\) | M1dep | attempt at a full expansion with correct multiplication of their 3 or 4 terms by one of the terms in the remaining bracket oe eg1 \(6x^3 - 8x^2 - 15x^2 + 20x\) or \(6x^3 - 23x^2 + 20x\) or \(12x^2 - 16x - 30x + 40\) or \(12x^2 - 46x + 40\) eg2 \(6x^3 + 12x^2 - 15x^2 - 30x\) or \(6x^3 - 3x^2 - 30x\) or \(-8x^2 - 16x + 20x + 40\) or \(-8x^2 + 4x + 40\) |
| \(6x^3 - 11x^2 - 26x + 40\) | A1 | fully correct simplified expansion allow terms written in a different order |
Additional guidance
| For the M marks terms may be seen in a grid | |
| First M1 do not allow any omissions or extra terms eg1 \(3x^2 + 6x - 8\) eg2 \(3x^2 + 6x - 4x - 8 + x^2\) | M0 M0 |