June 2016 Paper 1 Q15
15 Rationalise the denominator and simplify fully \(\qquad \dfrac{6}{\sqrt{7} + 2}\) [3 marks]
| Answer | Mark | Comments |
|---|---|---|
| \(\dfrac{6}{(\sqrt{7} + 2)} \times \dfrac{(\sqrt{7} - 2)}{(\sqrt{7} - 2)}\) | M1 | \(\dfrac{6}{(\sqrt{7} + 2)} \times \dfrac{(2 - \sqrt{7})}{(2 - \sqrt{7})}\) |
| Denominator = 3 or \(-3\) | A1 | |
| \(2(\sqrt{7} - 2)\) or \(2\sqrt{7} - 4\) | A1 |
Additional guidance
Correct answer seen, then error in factorising, do not penalise
\(\dfrac{6}{(\sqrt{7} + 2)} \times (\sqrt{7} - 2)\) followed by \(\dfrac{6\sqrt{7} - 12}{3}\) implies M1 A1 (they have 'recovered')