# Substituting Negative Numbers

In this worksheet, students substitute negative numbers into algebraic expressions.

Key stage:  KS 3

Curriculum topic:   Algebra

Curriculum subtopic:   Understand Expressions, Equations, Inequalities, Terms and Factors

Difficulty level:

### QUESTION 1 of 10

In this worksheet, we will learn how to substitute negative numbers.

Substitute the negative numbers into the expressions instead of the letter.

Example

Evaluate
 2x+3 4x
when X = -5

 2x(-5)+3 4x(-5)
=
 -10+3 -20
=
 -7 -20
=
 7 20

Remember: Multiplying or dividing two negative numbers gives a positive answer.

Multiplying or dividing one positive and one negative number, gives a negative answer.

Work out the following:

 3x + 4 5x
=  _______

when x = -5

Work out the following:

5x2 = _________  when x = -3

Work out the value of:

7x2 = _________  when x = -1

Work out the value of:

4x2 - 2 = _________  when x = -5

Work out the value of:

(7x)2 = _________  when x = -2

Work out:

8x2 = _________  when x = -1

Work out:

7(x - 1)2 = _________  when x = -2

Work out the following:

 2x + 2 3x
=  _______

when x = -4

Work out the value of:

(6x)2 = _________  when x = -2

Work out the value of:

6x2 = _________  when x = -2

• Question 1

Work out the following:

 3x + 4 5x
=  _______

when x = -5

11/25
EDDIE SAYS
 3x + 4 5x
=
 3(-5) + 4 5(-5)
=
 -15 + 4 -25
=
 11 25

• Question 2

Work out the following:

5x2 = _________  when x = -3

45
EDDIE SAYS
Remember to work out the power first 5 (-3)2 5 x 9 45
• Question 3

Work out the value of:

7x2 = _________  when x = -1

7
EDDIE SAYS
Remember to work out the power first 7 (-1)2 7 x 1 7
• Question 4

Work out the value of:

4x2 - 2 = _________  when x = -5

98
EDDIE SAYS
Remember to work out the power first 4 (-5)2 - 2 4 x 25 - 2 98
• Question 5

Work out the value of:

(7x)2 = _________  when x = -2

196
EDDIE SAYS
Remember to work out the brackets first (7 x -2)2 (-14)2 196
• Question 6

Work out:

8x2 = _________  when x = -1

8
EDDIE SAYS
Remember to work out the power first 8 (-1)2 - 2 8x 1 8
• Question 7

Work out:

7(x - 1)2 = _________  when x = -2

63
EDDIE SAYS
Remember to work out the bracket first, then the power. Remember to work out the power first 7(-2 -1)2 7 x (-3)2 7 x 9 63
• Question 8

Work out the following:

 2x + 2 3x
=  _______

when x = -4

1/2
EDDIE SAYS
 2x + 2 3x
=
 2(-4) + 2 3(-4)
=
 -8 + 2 -12
=
 1 2

• Question 9

Work out the value of:

(6x)2 = _________  when x = -2

144
EDDIE SAYS
Remember to work out the brackets first (6 x -2)2 (-12)2 144
• Question 10

Work out the value of:

6x2 = _________  when x = -2

24
EDDIE SAYS
Remember to work out the power first 6 (-2)2 6 x 4 24
---- OR ----

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