Higher June 2018 Paper 2 Q20

20 Martin did this question.

Here is how he answered the question.

\(\begin{aligned} \frac{14}{2 + \sqrt{3}} &= \frac{14 \times (2 - \sqrt{3})}{(2 + \sqrt{3})(2 - \sqrt{3})} \\[4pt] &= \frac{28 - 14\sqrt{3}}{4 + 2\sqrt{3} - 2\sqrt{3} + 3} \\[4pt] &= \frac{28 - 14\sqrt{3}}{7} \\[4pt] &= 4 - 2\sqrt{3} \end{aligned}\)

Martin’s answer is wrong.

Sian did this question.

Here is how she answered the question.

\(\begin{aligned} \frac{5}{\sqrt{12}} &= \frac{5\sqrt{12}}{\sqrt{12} \times \sqrt{12}} \\[4pt] &= \frac{5 \times 3\sqrt{2}}{12} \\[4pt] &= \frac{5\sqrt{2}}{4} \end{aligned}\)

Sian’s answer is wrong.