The slope is the ratio of the change in the y-value over the change in the x-value. Given any two points on a line, you can calculate the slope of the line by using this formula:
Given two points, P = (0, –1) and Q = (4,1), on the line, find the eqaution of the line.
Solution:Step 1: Calculate the slope.
slope = =
Step 2: Substitute m = , into the equation, y = mx + b, to get the equation
Step 3: Select one of the given points, for example (4, 1), and substitute the x and y values into the equation.
We, then, get that b = −1, which is the y-intercept.
Step 4: Subtitute b = −1 to get the equation.
y = x − 1
This video explains how to determine the equation of a vertical line given two points on the line.
This video explains how to determine the equation of a horizontal line given two points on the line.
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