1. X and Y Intercepts

2. X and Y Intercepts Essential Questions
How can x-intercepts and y-intercepts be determined?
How can equations be graphed using intercepts?

3. Y intercept
The y-intercept is the point where a line crosses the y axis.
At this point the value of x is 0.
To find the y-intercept, plug 0 in for x in the linear equation and solve for y.
y = 3x (0, -6)
y = 3(0) – 6
y = -6

4. X intercept
The x-intercept is the point where a line crosses the x axis.
At this point the value of y is 0.
To find the x-intercept, plug 0 in for y in the linear equation and solve for y.
y = 3x (2, 0)
0 = 3x – 6
6 = 3x
2 = x

5. Example of Finding Intercepts
-16x + 8y = -16
y-intercept x = 0
-16(0) + 8y = -16
8y = -16
y = -2
x-intercept y = 0
-16x + 8(0) = x = -16
x = 1
y-intercept = -2
x-intercept = 1

6. Example of Finding Intercepts
3x + 4y = 12
y-intercept x = 0
3(0) + 4y = 12
4y = 12
y = 3
x-intercept y = 0
3x + 4(0) = 12
3x = 12
x = 4
y –intercept = 3
x-intercept = 4

7. Example of Finding Intercepts
y = 2x – 2
y-intercept x =0
In this case the equation is written in slope-intercept form (y = mx + b); therefore, the -2 is the “b” or y-intercept
x-intercept y = 0
0= 2x – 2
2 = 2x
1 = x
x-intercept = 1

8. Find the Equation of the LineGiven the x- and y - intercepts
Write the intercepts as ordered pairs.
The x-intercept 4 is the ordered pair (4, 0).
The y-intercept -2 is the ordered pair (0, -2).
Calculate the slope.
Substitute the slope and the y-intercept (b) into the slope-intercept formula.

9. Example Write the equation of the line with x-intercept 3
and y-intercept 2.
x-intercept 3 = (3, 0); y-intercept 2 = (0, 2)
Slope:
y = mx + b