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2.03 Gradient-intercept form

Worksheet
Gradients and y-intercepts
1

Consider the following graphs of the equations y = x + 3, y = 2 x + 3 and \\y = 4 x + 3:

a

What is the same about all three equations?

b

What is the same about all three lines?

c

What can be concluded about the constants in equations and the y-intercepts of their graphs?

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

What does the following stand for in the equation of a line: y = mx + c?

a
m
b
c
3

State the y-intercept of the line y = - x + 6.

4

For each of the following equations:

i

State the y-intercept.

ii

State the gradient.

a
y = 7x - 8
b
y = -x + 5
c
y = -9x-3
d
y = 4 + 9x
e
y = -2x
f
y = - 1 - \dfrac{9 x}{2}
g
y = \dfrac{x-4}{5}
h
y = \dfrac{11 - 2x}{3}
5

For each of the following lines:

i

State the y-intercept.

ii

Find the gradient.

a
-4
-3
-2
-1
1
2
3
4
x
-4
-3
-2
-1
1
2
3
4
y
b
-4
-3
-2
-1
1
2
3
4
x
-4
-3
-2
-1
1
2
3
4
y
c
-4
-3
-2
-1
1
2
3
4
x
-4
-3
-2
-1
1
2
3
4
y
d
-4
-3
-2
-1
1
2
3
4
x
-4
-3
-2
-1
1
2
3
4
y
e
-4
-3
-2
-1
1
2
3
4
x
-7
-6
-5
-4
-3
-2
-1
1
2
3
4
y
f
-3
-2
-1
1
2
3
x
-4
-3
-2
-1
1
2
3
4
5
6
y
Equation from a line
6

For each of the following lines:

i

State the gradient.

ii

State the y-intercept.

iii

Find the equation of the line in gradient-intercept form.

a
-4
-3
-2
-1
1
2
3
4
x
-4
-3
-2
-1
1
2
3
4
y
b
-1
1
2
3
4
x
-4
-3
-2
-1
1
2
3
4
y
c
-1
1
2
3
4
x
-4
-3
-2
-1
1
2
3
4
y
d
-4
-3
-2
-1
1
2
3
4
x
-4
-3
-2
-1
1
2
3
4
y
e
-4
-3
-2
-1
1
2
3
4
x
-1
1
2
3
4
5
6
7
y
f
-4
-3
-2
-1
1
2
3
4
x
-35
-30
-25
-20
-15
-10
-5
y
g
-4
-3
-2
-1
1
2
3
4
x
-7
-6
-5
-4
-3
-2
-1
1
y
h
2
4
6
8
10
12
14
16
x
-1
1
2
3
4
5
6
7
y
i
-1
1
2
3
4
x
-4
-3
-2
-1
1
2
3
4
5
y
j
-4
-3
-2
-1
1
2
3
4
x
-1
1
2
3
4
5
6
7
y
7

Find the equation of the following lines:

a
-4
-3
-2
-1
1
2
3
4
x
-4
-3
-2
-1
1
2
3
4
y
b
-16
-14
-12
-10
-8
-6
-4
-2
x
-7
-6
-5
-4
-3
-2
-1
1
y
8

Consider the following table of values:

x-2024
y6420
a

Graph the line going through these points.

b

Write the equation of the line that goes through these points.

9

Write the equation of the following lines in gradient-intercept form:

a

A line that has a gradient of - 3 and crosses the y-axis at 1.

b

A line that has a gradient of 2 and a y-intercept of - 5.

c

A line that has a gradient of \dfrac{2}{3} and passes through the point \left(0, 3\right).

d

A line that has a gradient of \dfrac{3}{4}, and intersects the y -axis at - 1.

e

A line that has the same gradient as y = 7 - 3 x and the same y-intercept as \\ y = - 7 x - 8.

Graph of a line from an equation
10

Sketch the graph of a line with y-intercept of - 2 and gradient of 5.

11

Sketch the graph of the following linear equations:

a

y = - 4 x + 4

b

y = 2 x-1

c

y = 4 x + 3

d
y = - x + 4
e
y = 3 x - 8
f
y = - x - 2
g
y = - x + 3
h

y = 4 x - 1

12

Determine whether the following lines pass through the origin \left(0 , 0\right):

a

y = 6 x

b

y = \dfrac{x}{6}

c

y = 6 x - 6

d

y = 8 x + 8

e

y = 8 x

Equations of horizontal and vertical lines
13

State the equation of the following graphed lines:

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

Sketch the following lines on a number plane:

a
x = 2
b
x = -8
c
y = 1
d
y = -7
15

Consider the given table for the linear equation y = 0:

Does this represent the y-axis or x-axis?

x 4.5 0.5 3.5 8.5
y 0 0 0 0
16

Consider the given table for the linear equation x = 0:

Does this represent the y-axis or x-axis?

x0000
y- 5.5- 2.53.56.5
17

State the point of intersection of the following pairs of lines:

a

x = 6 and y = - 3

b

x = 1 and y = 5

c

x = -2 and y = - 1

d

x = 0 and y = 8

Applications
18

A cleaner charges a callout fee of \$90 plus \$30 per hour.

a

Write an equation to represent the total amount charged, y, by the cleaner as a function of the number of hours worked, x.

b

Sketch the graph of y against x for 0 \leq x \leq 6.

c

State the gradient of the line.

d

State the y-intercept.

19

Robert is running a 80 \text{ km} ultramarathon at an average speed of 15 \text{ km/h}.

a

Write an equation to represent the distance Robert has left to run, y, as a function of the number of hours since the start, x.

b

Sketch the graph of y against x for 0 \leq x \leq 6.

c

State the gradient of the line.

d

State the y-intercept.

20

Mario is running a 100 \text{ km} ultramarathon at an average speed of 9 \text{ km/h}.

a

Write an equation to represent the distance Mario has left to run, y, as a function of the number of hours since the start, x.

b

State the gradient of the function.

c

Describe what the gradient of the line represents in context.

d

State the y-intercept.

e

Describe what the y-intercept represents in context.

f

Find the distance Mario will have left to run after 4.5 hours.

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MS11-2

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