1. 4.7 Graphing Lines Using Slope Intercept Form
Goal: Graph lines in slope intercept form.

2. Slope-Intercept Form of the Linear Equation
y = mx + b m b
= slope
= y-intercept
Any linear equation which is solved for y is in slope-intercept form.

3. Find the slope and y-intercept of the following linear equations:
y = -2x - 1
y = 3x + 4
m = -2
b = -1
m = 3
b = 4 -2 1
y = x -
y = 5x 9 4 -2 -1
m =
m = 5
b = 0
b = 9 4

4. Write a linear equation in the form y = mx + b given the following.
m = 2, b = -3
y = 2x - 3
m = , b = 5

5. -2 -3 Graph the following linear equation using slope and y-intercept.
Steps y
1) Find the slope and y-intercept. +3 +2 x
2) Plot the y-intercept. -2
3) Plot the slope. -2 -3 2
m =
or m = -3 3
4) Draw line through points.

6. Graph the line which passes through (-2, 1) and has a slope of -3.
Steps y
1) Plot the point.
2) Write slope as fraction
and count off other points. -3
m = -3 -3 x = 1 3 +1
or m = -1
3) Draw line through points.

7. -3 -4 Graph the line which passes through (3, 2) and has a slope of .
Steps y +4
1) Plot the point. +3
2) Write slope as fraction
and count off other points. 3 x
m = 4 -3
or m = -4
3) Draw line through points.

8. Write a linear equation in slope-intercept form
to describe each graph. y = mx + b y y 8 x x -6 2 4
b = -4
b = 3
y = 2x + 3

9. Sometimes we must solve the equation for y before we can graph it.
The constant, b = 3 is the y-intercept.
The coefficient, m = -2 is the slope.

10. 1) Plot the y-intercept as a point on the y-axis
1) Plot the y-intercept as a point on the y-axis. The constant, b = 3, so the y-intercept = 3.
down 2
2) Plot more points by counting the slope up the numerator (down if negative) and right the denominator. The coefficient, m = -2, so the slope = -2/1.
right 1
down 2
right 1

11. Parallel Lines Graph the following on the coordinate plane.y x
Parallel lines have the same slope.

12. Lines are parallel! Same slope!
Tell whether the lines below are parallel.
1) 3x + y = y = -3x + 1
-3x x
y = -3x + 7
m = -3
y = mx + b
Same slope!
m = -3
Lines are parallel!