Part 20 - Rationalisation III | Maths Made Easy

Surds GCSE Maths Revision

Part 20 – Rationalisation III

Example:

Rationalise 2/(2-√3)

Worked Solution:

Use the formulae m/(n±√a)×(n∓√a)/(n∓√a)=(mn∓m√a)/(n^2-a²) and √ab≡√(a×b)≡ √a×√b

2/(2-√3)=2/(2-√3)×(2+√3)/(2+√3)=(2×2+2√3)/((2-√3)(2+√3))

=(4+2√3)/(4-2√3+2√3-√3×√3)

=(4+2√3)/(4-3)=(4+2√3)/1

=4+2√3


Your turn:

Rationalise \frac{2}{9-\sqrt{5}}

Your answer can be written in the for: \frac{a+\sqrt{5}}{b}

Enter your answer here:
a =
b =

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