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Use Substitution in Simple Algebraic Expressions

In this worksheet, students will substitute numbers for letters and work out the value of simple expressions with two variables.

'Use Substitution in Simple Algebraic Expressions' worksheet

Key stage:  KS 3

Year:  Year 7 Maths worksheets

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 x b.

 

Example

Work out the value of the following expression when a = 4 and b = -5

 

3a - 7 - 2b

 

Answer

3a - 7- 2b

= (3 x a) - 7 - (2 x b)

= (3 x 4) - 7 - (2 x - 5)

= 12 - 7 - -10

= 12 - 7 + 10

15

 

Did you remember the rules for negative numbers?

 

One negative and one positive makes a negative.

Two positives or two negatives makes a positive.

 

These facts will be very important in this activity!!

 

Are you ready to begin?

 

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