These are selected revision notes and practice questions. No original exam-year or paper references have been verified; these questions are not presented as authenticated past papers. Use your current textbook and teacher guidance for complete coverage.
To eliminate surds (square roots) from the denominator, multiply both numerator and denominator by the conjugate of the denominator.
Example: Rationalize $\frac{1}{\sqrt{7} - \sqrt{6}}$
$$\frac{1}{\sqrt{7} - \sqrt{6}} \times \frac{\sqrt{7} + \sqrt{6}}{\sqrt{7} + \sqrt{6}} = \frac{\sqrt{7} + \sqrt{6}}{(\sqrt{7})^2 - (\sqrt{6})^2} = \frac{\sqrt{7} + \sqrt{6}}{7 - 6} = \sqrt{7} + \sqrt{6}$$
Solution: Let $x = 0.235235235\dots$ (Eq 1).
Since 3 digits repeat, multiply both sides by $1000$:
$1000x = 235.235235\dots$ (Eq 2).
Subtracting Eq 1 from Eq 2:
$999x = 235 \implies x = \frac{235}{999}$.