Surds
Maths: Edexcel IGCSE Higher, topic 1.4.5
Surds
Surds are expressions like 3√6. They contain irrational numbers. These are numbers which can't be expressed as normal numbers or as a fraction. The rules for surds are:
Simplifying Surds
If the number inside the root has a factor which is a square number the surd can be simplified.
Example
Rationalising the Denominator
It is often easier to work with surds when there are no square roots on the bottom of a fraction. Removing surds from the bottom of a fraction is called ‘rationalising the denominator’.
Simple example
Advanced example
- To rationalise a denominator of the form a ± √b multiply by the denominator but with the sign in front of the root changed.
Exact form
- Leaving an answer in exact form means leaving any fractions, surds and constants like in the expression rather than giving the answer as a decimal.
Test yourself on Surds
Which of these are surds?
Which of these are surds?
Which of these are surds?
Which of these is another way of expressing
Which of these is another way of expressing