Surds - Rationalising the Denominator (Edexcel A-Level Mathematics): Flashcards

Bad presentation

Form with rational denominator

Multiply by $\frac{\sqrt{a}}{\sqrt{a}}$

Simplify surds first

$3\sqrt{5}$

$2\sqrt{5}$

$a - b\sqrt{c}$

Multiply by conjugate over itself

To rationalise $a+b\sqrt{c}$ denominators

No, bad in examiner's eyes

$7$

$\frac{6\sqrt{5}}{5}$