Aim #19: How do we graph lines by using the intercepts?
HW: Worksheet
Do Now:
Sketch the graph of a line with each of the following slopes:
Positive
Negative
Zero
Undefined
What is the least amount of points we need to draw a line? ______
Intercepts
The y-intercept is where the graph of an equation crosses the y-axis.
To find this algebraically set x = 0 and solve for y.
The x-intercept is where the graph of an equation crosses the x-axis.
To find this algebraically set y = 0 and solve for x.
x-intercept
Find the x and y intercepts of 2x - 8y = 48.
y-intercept
Find the intercepts and then graph the following linear equations.
1) -3x + 15y = 30
2) .25x = .75y - 1.50
3) 4x + 5y = 21
4) -5x + 4y = 20
Now let us look at some equations with only one variable to see what happens.
5) 4x = -16
6) -3y = -21
Find the x and y intercepts of the following and graph. What do you notice?
7) y = x
8) y = -x
Find the x and y intercepts of the following equations:
9) 3x - y = 6
10) 2x + 4y = 8
11) 5x - 7y = 12
12) 3x - 9y = -18
Sum It Up!!
The y-intercept of a graph is when it crosses the y-axis. To find this algebraically
we plug in x=0 to the equation.
The x-intercept of a graph is when it crosses the x-axis. To find this algebraically
we plug in y=0 to the equation.