An equation of the line can be determined when the coordinates of two points of the line are given.
1. Find the slope of the line through the given points.
Formula :
y2 - y1
m = _______
x2 - x1
Let (x1, y1) = (-4, 0)
(x2, y2) = (0 , -3)
-3 - 0
= ________
0 - (-4)
-3
m = ____
4
2. Write the slope - intercept form, find b given m = -3/4, use either of the points.
y = mx + b , m = -3/4, (x,y) = (0, -3)
-3 = -3/4(0) + b
-3 = b
The slope is -3/4 and y-intercept = -3
y = mx + b
<<< Equation written in slope -intercept form
4y = -3x - 12
3x + 4y + 12 = 0 <<<<<<<< Equation in standard form
(