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Quiz yourself on SurdsGet your flashcardsBuild my revision planTrack my progressHigher Level: Rationalising Two Term Denominators
For denominators with two terms, use the conjugate:
- Conjugate of (a + √b): (a - √b)
- Why it works: (a+√b)(a-√b) = a² - b (no surd!)
Example: Rationalise 1/(3 + √7)
Multiply by (3 - √7)/(3 - √7):
= (3 - √7)/[(3 + √7)(3 - √7)]
= (3 - √7)/(9 - 7)
= (3 - √7)/2
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