Simplifying Surds (Cambridge O Level Maths)
Revision Note
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AmberExpertise
Maths
Surds & Exact Values
What is a surd?
- A surd is the square root of a non-square integer
- Using surds lets you leave answers in exact form
- e.g. rather than
How do I calculate with surds?
- Multiplying surds
- You can multiply numbers under square roots together
- eg.
- Dividing surds
- You can divide numbers under square roots
- eg.
- Factorising surds
- You can factorise numbers under square roots
- eg.
- Adding or subtracting surds is very like adding or subtracting letters in algebra – you can only add or subtract multiples of “like” surds
- eg.
- Be very careful here, you can not add or subtract numbers under square roots
- Think about
- It is not equal to
Exam Tip
- If you are working on an exam question and your calculator gives you an answer as a surd, leave the value as a surd throughout the rest of your calculations to make sure you do not lose accuracy throughout your questions
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