 # Algebra: Substitution with Squares and Square Roots (1)

In this worksheet, students 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:   ### QUESTION 1 of 10

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 - 2b

= 3 × a × a - 7 - 2 × b

= 3 × 4 × 4 - 7 - 2 × √9

= 48 - 7 - 2 × 3

= 48 - 7 - 6

= 35

Work out the value of the following expression when a = 4

3a2

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

3a2

Work out the value of the following expression when a = 4

√a

Work out the value of the following expression when a = 4

5√a

Work out the value of the following expression when a = 16

4√a

Work out the value of the following expression when a = 3

4a2 - 3

Work out the value of the following expression when a = 3

4a2 + 3a

Work out the value of the following expression when a = 4

2√a - 3

Work out the value of the following expression when a = 25

2√a - a

Work out the value of the following expression when a = 4

3√a + a2

• Question 1

Work out the value of the following expression when a = 4

3a2

48
• Question 2

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

3a2

48
• Question 3

Work out the value of the following expression when a = 4

√a

2
• Question 4

Work out the value of the following expression when a = 4

5√a

10
• Question 5

Work out the value of the following expression when a = 16

4√a

16
• Question 6

Work out the value of the following expression when a = 3

4a2 - 3

33
• Question 7

Work out the value of the following expression when a = 3

4a2 + 3a

45
• Question 8

Work out the value of the following expression when a = 4

2√a - 3

1
• Question 9

Work out the value of the following expression when a = 25

2√a - a

-15
• Question 10

Work out the value of the following expression when a = 4

3√a + a2

22
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