Writing the Equation of a Line

Page 6, 7, 8

Slope – Intercept Equation

bmxy

m = slope

b = y-intercept

y-intercept

b=2

1. Write the equation of a line given slope m that passes through the given point.

a) m=3 (1,5) c) m=1/2 (-2,-3)

bmxy Sub in

b )1(35

b353 3 b2

23 xy

bmxy Sub in

b )2(2

13

b 131 1 b 2

22

1 xy

2. Through the given point, draw the graph of the line with the given slope m.

3

2 ),6,4( d. m

3. Write the equation of a line that passes through the given points.

c) (-1,3), (1,-1)

bmxy b )1(23

b232 2 b1

-4

2

x

ym

22

4

m 2

bmxy

1

xy

Sub in

1b

4. Write the equation of a line whose slope and y-intercept are respectively:

a) 4,5 b) 2,-5

m=4, b=5

bmxy

54 xy

m=2, b=-5

bmxy

52 xy

Homework

Page 6#1b,d,3f,5e,6f

1. Write the equation of a line given slope m that passes through the given point.

b) m=2 (-3,5) d) m=2/3 (-1,4)

bmxy Sub in

b )3(25

b 656 6 b11

112 xy

bmxy Sub in

b )1(3

24

b3

24

3

2

3

2

b3

24

3

24

3

2 xy

3. Write the equation of a line that passes through the given points.

c) (12,-5), (-4,-1)

bmxy

b )4(4

11

b 111 1 b 2

21

21

xx

yym

16

4

)4(12

)1(5

m

bmxy

24

1- xy

Sub in

4

1m

5e) Find the slope and y-intercept of:

xx 2 2 92 xy

92 yx

2m9b

6f) Determine the coordinates of the point at which the graph intersects the y-axis.

xx 3 3 xy 3122

01223 yx

12 12 1232 xy

2 2

62

3 xy

(0,6)

B=6