4.7 Graphing Lines Using 4.7 Graphing Lines Using Slope Intercept FormSlope Intercept Form

Goal: Graph lines in slope intercept form.

Slope-Intercept Form of the Linear Equation

y = mx + bm

= slope

b

= y-interceptAny linear equation which is solved for y

is in slope-intercept form.

Find the Find the slopeslope and and y-intercepty-intercept of the of the following linear equations:following linear equations:

y = 3x + 4m = 3 b = 4

y = -2x - 1m = -2 b = -1

y = x -9 4

m = b =9 4

-2 1

-2 -1

y = 5x

m = 5 b = 0

Write a linear equation in the form y = mx + b given the following.

m = 2, b = -3

m = , b = 5

y = 2x - 32

32

53

y x

+3+2

-3

Graph the following linear equation using slope and y-intercept.

x

y

1) Find the slope and y-intercept.

Steps

2) Plot the y-intercept.

m = 23

or m = -2

4) Draw line through points.

y x 2

31

3

2m b 1

3) Plot the slope.-2

-3

+1

-3

Graph the line which passes through Graph the line which passes through (-2, 1) and has a slope of (-2, 1) and has a slope of -3-3.

x

y1) Plot the point.Steps

2) Write slope as fractionand count off other points.

m = -3 =-3

1or m =

3

-1

3) Draw line through points.

+4

+3

Graph the line which passes through (3, 2) and

has a slope of .

x

y

1) Plot the point.

Steps

2) Write slope as fractionand count off other points.

m = 34

or m = -3

-43) Draw line through points.

34

Write a linear equation in slope-intercept form

to describe each graph. y = mx + b

x

y

x

y

b = 3m 2

1y = 2x + 3

b = -43

1

m

y x 1

34

4

8

-62

Parallel LinesGraph the following on the coordinate plane.

y x 1

23 y x

1

21

m 1

2

b 3

m 1

2

b 1x

y

Parallel lines have the same slope.

-3x -3x

Tell whether the lines below are parallel.

1) 3x + y = 7 y = -3x + 1

y = -3x + 7

m = -3

y = mx + b

m = -3

Lines are parallel!

Same slope!