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CanadaON
Grade 8

4.03 Graphs of linear equations

Worksheet
Intercepts
1

For each of the following graphs:

i

State the value of the x-intercept.

ii

State the value of the y-intercept.

a
-3
-2
-1
1
2
3
x
-3
-2
-1
1
2
3
y
b
-2
-1
1
2
3
4
5
6
x
-2
-1
1
2
3
4
5
6
y
c
-4
-3
-2
-1
1
2
3
4
x
-4
-3
-2
-1
1
2
3
4
y
d
-2
-1
1
2
3
4
5
x
-4
-3
-2
-1
1
y
2

Given each linear equation and its graph, state the coordinates of the y-intercept:

a
y = 4x - 5
-4
-3
-2
-1
1
2
3
4
x
-7
-6
-5
-4
-3
-2
-1
1
2
3
4
5
6
7
y
b
y = \dfrac{x}{2} + 3
-6
-4
-2
2
4
6
x
-2
2
4
6
8
y
3

Consider the following graph of the line y = - 2 x + 3:

a

State the the y-value, when x is 0.

b

Explain the relationship between the value of the y-intercept and the equation of the line.

c

If the equation of a line is y = m x + b, state the value of the y-intercept.

-4
-3
-2
-1
1
2
3
4
x
-4
-3
-2
-1
1
2
3
4
5
6
7
y
4

Consider the following three linear equations and their corresponding graphs:

y = x + 4, \, y = 2 x + 4, \, y = 4 x + 4

a

What do all of the equations have in common?

b

What do all of the graphs have in common?

c

What conclusion can be made about lines that have the form y = m x + 4?

-8
-6
-4
-2
2
4
6
8
x
-4
-2
2
4
6
8
10
y
5

Find the value of the y-intercept of the following lines:

a

y = 7 x + 3

b

y = 3 x - 5

c

y = - 8 x - 3

d

y = - 8 x + 4

e

y = 9 x

f

y = 2

g

y = 2x+\dfrac{2}{3}

h

y = \dfrac {3 x + 8}{5}

6

Determine whether the following equations represent lines that will cross the y-axis at 2:

a

y = 5 x + 2

b

y = 2 - x

c

y = 2 x

d

y = 2 x - 4

e

y = x + 2

f

y = x - 2

g

y = 2

h

y = \dfrac{x + 4}{2}

7

The x-intercept occurs when y=0. Find the value of the x-intercept for the following lines:

a

y = 2 x - 2

b

3x + y = -3

c

y = 4 x - 8

d

2y + x = -3

e

y = 9 x

f

2y + 2x = 4

g

3x - 5y = 1

h

x = \dfrac {3 y + 10}{5}

8

For each of the following equations:

ii

Find the coordinates of the y-intercept.

i

Find the coordinates of the x-intercept.

iii

Use the intercepts to sketch the graph of the line.

a

y = 2 x - 4

b

y = - 2 x + 2

c

y = 3 x - 3

d

y = - 4 x + 8

Lines through the origin
9

Consider the linear equation y = 5 x .

a

Find the coordinates of the y-intercept.

b

Find the coordinates of the x-intercept.

c

Find the value of y when x = 2.

d

Hence, sketch the graph of the line.

10

Consider the linear equation y = - \dfrac {5 x}{4}.

a

Find the coordinates of the y-intercept.

b

Find the coordinates of the point on the line where x = 4.

c

Hence, sketch the graph of the line.

11

If a line has equation y=mx + b, explain how you can tell if the line will pass through the origin.

12

Determine whether the following equations represent lines that will pass through the origin:

a

y = 8 x - 8

b

y = \dfrac {x}{8}

c

y = - 6 x

d

y = 8 x

e

y = \dfrac {x}{8}

f

y = 0

g

y = - x

h

y = - 6 x - 6

Slope
13

Consider the line graph shown:

a

State the y-value when x=0.

b

State the y-value when x=1.

c

When the x-value increases by 1, by how much does the y-value change?

d

Hence state the slope of the line, m.

e

The equation of this line is y = 2 x + 4. Explain how to find the slope from the equation of the line.

-4
-3
-2
-1
1
2
x
-2
-1
1
2
3
4
5
6
7
y
14

Consider the following three linear equations and their corresponding graphs:

y = 4 x + 3, \, y = 4 x + 6, \, y = 4 x - 3

a

What do all of the equations have in common?

b

What do all of the graphs have in common?

c

What conclusion can be made about lines that have the form y = 4 x + b?

-5
-4
-3
-2
-1
1
2
3
4
5
x
-5
-4
-3
-2
-1
1
2
3
4
5
y
15

Find the slope, m, of the following linear equations:

a

y = 9 x + 3

b

y = - 7 x + 5

c

y = \dfrac{5x}{4} + 2

d

y = -x + 5

16

From the following list of equations, select the lines that have the same slope:

  • y = 2 + 7 x

  • y = \dfrac {x}{7} + 2

  • y = 5 - 7 x

  • y = 7 x

  • y = 5 x + 7

  • y = 7 x - 2

17

For each linear equation:

i

Find the value, m, of the slope.

ii

Find the value, b, of the y-intercept.

a

y = 2 x + 9

b

y = 5 x - 6

c

y = - 5 x + 8

d

y = - 4 x - 2

e

2y = 8 x - 1

f

3y = -6 x - 2

g

y - 5x = 4

h

2y - 3x = 6

18

Given the values of m and b, write the equation of the line:

a

m=2, b= 5

b

m=-3, b= 2

c

m=-2, b= -1

d

m=4, b= 0

e

m=0, b= -7

f

m=0, b= 4

g

m=\dfrac{1}{2}, b= -2

h

m=-\dfrac{3}{4}, b= \dfrac{1}{2}

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Outcomes

8.B2.8

Compare proportional situations and determine unknown values in proportional situations, and apply proportional reasoning to solve problems in various contexts.

8.C1.1

Identify and compare a variety of repeating, growing, and shrinking patterns, including patterns found in real-life contexts, and compare linear growing and shrinking patterns on the basis of their constant rates and initial values.

8.C1.2

Create and translate repeating, growing, and shrinking patterns involving rational numbers using various representations, including algebraic expressions and equations for linear growing and shrinking patterns.

8.C4

Apply the process of mathematical modelling to represent, analyse, make predictions, and provide insight into real-life situations.

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