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5.06 Finding the equation of a straight line

Worksheet
Point-gradient formula
1

For the following graphs:

i

State the value of the x-intercept.

ii

State the value of the y-intercept.

a
-1
1
2
3
4
x
-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
-1
1
2
3
4
x
-5
-4
-3
-2
-1
1
y
d
-4
-3
-2
-1
1
2
3
4
5
6
x
-1
1
2
3
4
y
e
-4
-3
-2
-1
1
2
3
4
x
-4
-3
-2
-1
1
2
3
4
y
f
-2
-1
1
2
3
4
x
-5
-4
-3
-2
-1
1
2
y
2

For each of the following tables of values:

i

Find the gradient, m.

ii

Find the y-intercept, c.

iii

Write the equation of the line expressing the relationship between x and y.

iv

Complete the table of values.

a
x0123424
y0481216
b
x0123421
y914192429
c
x0123425
y- 23- 21- 19- 17- 15
d
x0123470
y272217127
3

For each of the following tables of values:

i

Find the equation of the line expressing the relationship between x and y.

ii

Complete the table of values.

a
x123419
y5101520
b
x123416
y- 3- 6- 9- 6
c
x123460
y14710
d
x123480
y- 14- 22- 30- 38
e
x1234-15
y82746658
4

Find the equation that corresponds to each of the following tables:

a
x- 10123
y741- 2- 5
b
x12345
y58111417
c
x- 8- 7- 6- 5- 4
y- 37- 32- 27- 22- 17
d
x34567
y-1- 3- 5- 7- 9
5

Find the equation of the following lines:

a

A line that passes through the point A \left( - 5 , - 4 \right) and has a gradient of - 4.

b

A line that passes through the point A \left( - \dfrac{4}{5} , - 4 \right) and has a gradient of 2.

c

A line that passes through Point A \left( - 4 , 3\right) and has a gradient of 4.

d

A line that passes through Point A \left(7, - 6 \right) and has a gradient of - 3.

e

A line that passes through the point A \left(3, 5\right) and has a gradient of - \dfrac{5}{2}.

f

A line that passes through the point A \left(4, 3\right) and has a gradient of - 3\dfrac{1}{3}.

g

A line that passes through the point A \left( - 4 , 3\right) and has a gradient of - 9.

h

A line that passes through the point A \left( - \dfrac{5}{9} , 7\right) and has a gradient of 7.

i

A line that passes through the point A \left(8, 1\right), and has a gradient of \dfrac{5}{2}.

j

A line that passes through the point A \left( - 4 , 5\right) and has a gradient of 3\dfrac{1}{2}.

6

For each of the following lines:

i

Find the equation of the line.

ii

Sketch the graph of the line.

a

A line has gradient 2 and passes through the point \left( - 5 , - 3 \right).

b

A line has gradient - \dfrac{3}{2} and passes through the point (- 2, 2).

c

A line has gradient - \dfrac{2}{5} and passes through the point \left( - 10 , 2\right).

d

A line has gradient - 3 and passes through the point \left(2, - 12 \right).

7

Consider the line with equation 2 x + y - 8 = 0.

a

Find the x-intercept of the line.

b

Hence, find the equation of a line with a gradient of - 4 that passes through the x-intercept of the given line.

8

Find, in general form, the equation of a line which has a gradient of \dfrac{4}{7} and cuts the x-axis at - 10.

9

For each of the following lines:

i

Find the gradient of the line.

ii

Find the equation of the line.

a

A line passes through the points \left(2, - 7 \right) and \left( - 5 , 6\right).

b

A line passes through the points \left(3, - 3 \right) and \left(5, - 11 \right).

c

A line passes through the points A \left( - 6 , 7\right) and B \left( - 8 , - 4 \right).

10

Identify which of the following equations of straight lines have a gradient of 5 and pass through the point A \left(-1, - 4 \right):

a

\dfrac{y + 4}{x + 1} = 5

b

\dfrac{x + 1}{y + 4} = 5

c

\dfrac{- 4 - y}{-1 - x} = 5

d

\dfrac{y + 1}{x + 4} = 5

11

Write down the equations of three lines that pass through the point (1, 3). Explain how your lines are different.

Parallel lines
12

Find the equation of the following lines:

a

A line that is parallel to the x-axis and passes through \left( - 10 , 2\right).

b

A line that is parallel to the y-axis and passes through \left( - 7 , 2\right).

c

A line that is parallel to the line y = - 3 x - 8 and cuts the y-axis at - 4.

13

A line goes through A \left(3, 2\right) and B \left( - 2 , 4\right):

a

Find the gradient of the given line.

b

Find the equation of another line that has a y-intercept of 1 and is parallel to this line.

14

Consider line L_1 with equation: 5 x - 4 y + 2 = 0.

a

Find the gradient of a line, L_2, that is parallel to L_1.

b

Find the equation of L_2 using the point-gradient formula, given that it passes through Point A \left( - 4 , 6\right). Express the equation in general form.

15

Find the equation of the following lines:

a

Passes through the point \left(9, - 5 \right) and is parallel to the line y = - 5 x + 2.

b

Passes through the point \left(-2, -4\right) and is parallel to the line y = 2x+13.

c

Passes through the point \left(10, 6\right) and is parallel to the line y = -6x-4.

d

Passes through the point \left(-3, 7\right) and is parallel to the line y = -12x+5.

Applications
16

A line has a gradient of \dfrac{3}{10} and passes through the midpoint of A \left( - 6 , - 6 \right) and B \left(8, 8\right).

a

Find the coordinates of M, the midpoint of AB.

b

Find the equation of the line in general form.

17

Consider the lines L_{1}, y = - 4 x + 5, and L_{2}, y = x - 1.

a

Find the midpoint M of their y-intercepts.

b

Find the equation of the line that goes through the point M and has gradient \dfrac{1}{3}. Express the equation in general form.

18

A circle with centre C \left(11, 13\right) has a diameter with end points A \left(5, 14\right) and B \left(p, q\right).

a

Find the value of p.

b

Find the value of q.

c

Find the equation of the line passing through B with gradient \dfrac{9}{2}.

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Outcomes

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VCMNA310

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