Edexcel A Level Maths: Pure

Revision Notes

A LevelMaths: PureEdexcelRevision Notes2. Algebra & Functions2.1 Laws of Indices & Surds2.1.3 Surds - Rationalising the Denominator

2.1.3 Surds - Rationalising the Denominator

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Surds - Rationalising the Denominator

What does it mean to rationalise a denominator?

  • Rationalising a denominator changes a fraction with surds in its denominator, into an equivalent fraction where the denominator is a rational number (usually an integer) and any surds are in the numerator

 Explanation diagram, A Level & AS Level Pure Maths Revision Notes

  • There are three cases you need to know how to deal with when rationalising denominators:

2.1.3 List of rationalising denominator cases, Edexcel A Level Maths: Pure revision notes

Exam Tip

  • If an exam question asks you to give an answer, for example, "in the form p + q√3 , where p and q are rational numbers", this does NOT mean that p and q have to be integers, or positive!
  • Remember: both integers and fractions (both positive and negative) are rational numbers

Worked example

Rationalising the Denominator Example, A Level & AS Level Pure Maths Revision Notes

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