# Practise Using Algebraic Substitution with Squares and Square Roots

In this worksheet, students will substitute numbers into expressions containing squares and square roots.

Key stage:  KS 3

Curriculum topic:   Algebra

Curriculum subtopic:   Substitute Numerical Values for Formulae/Expressions

Difficulty level:

#### Worksheet Overview

When we substitute a number for a letter, we simply replace the letter with the number.

However, we must remember that 4b means 4 × b and 4b2 means 4 × b × b.

Example

Work out the value of the following expression when a = 4 and b = 9

3a2 - 7 - 2√b

3a2 - 7 - 2√b

3 × a × a - 7 - 2 × √b

3 × 4 × 4 - 7 - 2 × √9

= 48 - 7 - 2 × 3

= 48 - 7 - 6

35

Let's try some questions now. Remember that you can check back to this introduction at any point by clicking on the red button at the side of the screen.

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