On day 7 of this unit, you learned to write an equation for a line given the slope of the line and the y-intercept of the line.
This lesson will teach you how to write the equation of a line given the slope of the line and any point on the line.
Example:
Write the equation of the line that passes through the point (4, -2) and has a slope of 2. Write the equation in slope-intercept form.
Solution:
The slope m is 2. Find the y-intercept b using m=2 and the point (4, -2) where x=4 and y=-2.
Substitute into the slope-intercept equation.
y = mx + b
-2 = 2(4) + b
-2 = 8 + b
-10 = b
Write the equation using m=2 and b=-10.
y = 2x + (-10)
y = 2x - 10
The equation of the line is y = 2x - 10.
Assignment:
Write an equation of the line that passes through the point and has the given slope. Write the equation in slope-intercept form.
1. (1, 2), m = 4
2. (-2, 3), m = -2
3. (-4, 3), m = 0
4. (3, -2), m = 4
5. (2, 5), m = 1/2
6. (-3, 2), m = -1/3
7. (0, -8), m = 6
8. (5, 0), m = -2
9. (-2, 2), m = 4
10. (-3, -5), m = -2
Return to Unit Home Page