Rationalising denominators
Edexcel GCSE Maths revision on Rationalising denominators. Aligned to the Pearson Edexcel GCSE Mathematics 1MA1 specification. This bank has 16 practice questions on this topic.
Sample questions (3 of 16)
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Question 1
What is the result of rationalising the denominator of 1 divided by the square root of 3?
- A) square root of 3 over 3
- B) one third of square root 2
- C) three divided by square root 3
- D) square root of 3 divided by 9
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Answer: square root of 3 over 3
Multiplying the fraction by root 3 over root 3 results in root 3 divided by 3. A common misconception is to simply remove the radical without adjusting the numerator.
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Question 2
When 5 divided by the square root of 5 is rationalised, what is the final simplified value?
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Answer: 5
Multiplying by the square root of 5 over the square root of 5 gives 5 multiplied by the square root of 5, all divided by 5. This simplifies to exactly the square root of 5.
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Question 3
Which expression is equivalent to 2 divided by the square root of 2?
- A) square root of 2
- B) one over root 2
- C) two times root 4
- D) four divided by 2
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Answer: square root of 2
Since 2 is equivalent to the square root of 2 multiplied by the square root of 2, dividing by the square root of 2 leaves you with just the square root of 2. Students often mistakenly simplify this to 1.
Want to test yourself on the remaining cards for this topic?
13 more questions on Rationalising denominators — plus mistakes tracking and spaced repetition across the whole Maths spec.