# Subtract two surds

## Lesson details

### Key learning points

1. In this lesson, we will learn how to subtract one surd from another where no prior simplification is needed.In these cases, the surds will all have the same root.

### Licence

This content is made available by Oak National Academy Limited and its partners and licensed under Oak’s terms & conditions (Collection 1), except where otherwise stated.

## Video

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## Worksheet

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## Starter quiz

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### 3 Questions

Q1.
Which number is not a surd?
√2
√5
√7
Q2.
Simplify 6√7+5√7
√7
11√14
30√7
Q3.
A piece of wood has been cut up into three equal pieces as shown. What was the original total length of the piece of wood?
4√5
6√15
8√5

## Exit quiz

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### 3 Questions

Q1.
Simplify 6√2 - 4√2
√2
10√2
2
Q2.
Simplify 6√7 - 5√7
11√14
30√7
Option 4
Q3.
A piece of wood is shown. It is 7√5 m long. A piece of length 2√5 m is cut away. How long is the piece of wood now?
14√5 m
15√5 m
Correct answer: 5√5 m
9√5 m