Specimen 2020 Paper 1 Q16
16 The coefficient of the \(\ x^4\ \) term in the expansion of \(\quad (2x + a)^6 \quad\) is 60
Work out the possible values of \(a\). [4 marks]
| Answer | Mark | Comments |
|---|---|---|
| \(15(2x)^4(a)^2\) | M1 | |
| \(15 \times 16a^2 = 60\) or \(240a^2 = 60\) | M1dep | oe |
| \(\sqrt{\dfrac{\text{their } 60}{\text{their } 240}}\) or \(\dfrac{1}{2}\) or \(-\dfrac{1}{2}\) | M1dep | oe |
| \(\dfrac{1}{2}\) and \(-\dfrac{1}{2}\) | A1 | oe |