Objective To write a linear equation given

1
Objective- To write a linear equation given two
points.
y mx b
1
Write the equation of the line which contains
y x b
3
1
5 (4) b
(-2, 3) (4, 5)
3
(x, y)
4
y2- y1
5 b
y
3
Slope (m)


x2- x1
x
4
15
4
b 5 -
-

5 - 3
3
3
3
2
Slope (m)


11
4 - -2
6
b
3
1
11
1
y x
m
3
3
3
2
Write the equation of the line which contains
(0, -3) (4, 8)
y mx b
(x, y)
11
y x b
y2- y1
4
y
Slope (m)


x2- x1
11
x
8 (4) b
4
8 - -3
11
Slope (m)


4 - 0
8 11 b
4
11
b 8 - 11
-3
m
4
b -3
11
y x - 3
4
3
Suppose a 5 minute overseas call costs 5.91 and
a 10 minute call costs 10.86. Write an equation
which describes cost y in terms of x minutes.
(minutes, cost)
(x, y)
(5, 5.91) (10, 10.86)
y mx b
y2- y1
10.86 - 5.91
y 0.99x b
m

x2- x1
10 - 5
5.91 0.99(5) b
4.95
0.99
m

5.91 4.95 b
5
-4.95 -4.95
0.96 b
y 0.99x 0.96
4
Use the x-y chart below to write a linear
equation that satisfies all the points.
x
y
2 6 4 16 7 31 9 41 14
66
5
Objective- To write linear equations to describe
situations and solve problems.
Snowflake Problem
Instance 1 2
3 4
Number of Chips 7 13
19 25
I
C
Let I Instance or Design .
1 7 2 13 3 19 4 25 5 31
Let C Number of Chips Used.
6
C is dependent on I
6
6
C ___I ___
6
1
6
6
Use the x-y chart below to write a linear
equation that satisfies all the points.
x
y
Choose two points to find equation!
2 6 4 16 7 31 9 41 14
66
y mx b
(4, 16) (7, 31)
10
y2- y1
15
y 5x b
m
x2- x1
10
16 5(4) b
31 - 16
25
16 20 b
m
7 - 4
-20 -20
15
-4 b
m
3
m 5
y 5x - 4
7
When a new kitten was 6 weeks old it weighed 8
ounces. When it was 10 weeks old it weighed 10
ounces. Write a linear equation which
describes its weight y in terms of its age in
weeks x.
(age, weight)
(x, y)
(6, 8) (10, 10)
y mx b
y2- y1
10- 8
y 0.5x b
m

x2- x1
10 - 6
8 0.5(6) b
2
0.5
m

8 3 b
4
-3 -3
5 b
y 0.5x 5