Download - Graphing Linear Equations Lesson
Essential Question: How do you graph linear equations using point plotting, intercepts, the slope-
intercept form, and the graphing calculator?
In order to graph using point plotting, you will need to create a table.
You will need to choose at least 3 numbers for x and “plug” them into the equation to find corresponding y values.
For Example:Graph y = 2x - 1
x y
Choose x values
“plug” x into the equation
Plot the points
-1 2(-1)-1=-3
0 2(0)-1 = -1
1 2(1)-1 = 1
Graph using point plotting32
1 xy
x y
-2
0
2
2
1
2
1
2
1
(-2) + 3 = 2
(0) + 3 = 3
(2) + 3 = 4
To graph using intercepts, you will need to find both theX and the y intercept
To find the x-intercept, substitute “0” for y and solve for x
To find the y – intercept, substitute “0” for x and solve for y
For example: y = 4x + 8
X-intercept:0 = 4x + 8 -8 = 4x -2 = x
Y – Intercept:Y = 4(0) + 8 Y = 8
Graph 2x + 3y = 6 using intercepts.
X-intercept:2x + 3(0) = 6 2x = 6 X = 3
Y-intercept:2(0) + 3y = 6 3y = 6 Y = 2
To graph a linear equation, you will need to find the slope and the y-intercept for the equation.
Remember: y = mx + b
slope Y-intercept (the point where the graph crosses the y-axis)
Graph 13
2 xy Slope =
Y-intercept =
3
2
1
1. Plot the y-intercept
2. Use the slope to find the next point
Slope = “rise over run”
Graph 2x + 5y = 10 using the slope-intercept form: (put the equation in slope-intercept form first)
2x + 5y = 10
5y = 10 – 2x
y = 2 – 2/5 x
slope = -2/5y – intercept = 2
A negative slope means you will go down then right from the y-intercept
Use the link below to access an online graphing calculator:
When using the calculator, you will first need to have the equationin slope-intercept form (y = mx + b)
http://www.coolmath.com/graphit/index.html
Then simply key in the equation and hit EVAL to see the graph
Graph on the graphing calculator42
1 xy
Graph 3x – 5y = 9 on the graphing calculator. (First you will need to solve for y).
3x – 5y = 9-5y = 9 – 3x
5
9
5
3
xy
Put the above equation into thegraphing calculator and click EVAL