Graphing Using Slope-Intercept Form Lesson 3.1 Core Focus on Linear Equations.
2.3 Graphing Linear Equations in Slope-Intercept Form.
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Transcript of 2.3 Graphing Linear Equations in Slope-Intercept Form.
2.3 Graphing Linear Equations in Slope-Intercept Form
Intercepts
X-intercept
• Graph crosses the x axis
• It occurs when y=0
• (x- intercept, 0)
Y-intercept
• Graph crosses the y-axis
• It occurs when x=0
• (0, y-intercept)
4
3
2
1
-1
-2
-3
-6 -4 -2 2 4 6
A
B
y - intercept
x - intercept
y
X
Slope-Intercept Formy = mx + b
slopeslope y-intercepty-intercept
Find the slope and y-intercept ofy = -5x + 6
5m 6b
If the equation is not in y=mx +b form….
Solve for y
Find the slope and y-intercept of2y = 7x - 4
7
2m 2b
2 2 2
72
2y x
Find the slope and y-intercept of2x + 3y = 6-2x -2x
3y = - 2x + 63 3 3
23
2 xy
2
3m 2b
Find the slope and y-intercept of-7x - 5y = 25+7x +7x
-5y = 7x + 25-5 -5 -5
55
7 xy
7
5m 5b
Steps To Graph Using y=mx+bSlope Intercept From:
• 1.) Solve for y so your equation is y=mx+b• 2.) Plot your b (y-intercept) on the y-axis• 3.) From your y intercept use your slope to
go up(+) or down (-) and right and plot your 2nd point
• 4.) Now that you have 2 points draw your line
5
4
3
2
1
-1
-2
-3
-4
-8 -6 -4 -2 2 4 6
Using y-intercept and slope, graph:
52
3y x
5
4
3
2
1
-1
-2
-3
-4
-8 -6 -4 -2 2 4 6
Using y-intercept and slope, graph:
24
5y x
Using y-intercept and slope, graph:
3 7y x
How to Identify the x-intercept
Algebraically
• Set y=0 and solve for x
Geometrically
• Look at where the graph crosses the x axis (can only be done if graph is precise)
Identify the x-intercept: y-10 = -5x
Algebraically Geometrically
10 5y x 0 10 5x
10 5x 5 52 x(2,0)
5 10y x 5
, 101
m b
Assignment
TB: Page 62 (1,2,4-24 even, 29-33 all)