Find the Equation Of A Line Given Its Slope And A Point On The Line

There are 2 ways to find the equation of a line from its slope and a point on the line. Let us illustrate the 2 methods in the following example..

Example :

Find the equation of a line with slope – and passing through (–3, 1).

Method 1

Step 1 : Let (x, y) be a point on the line other than (–3, 1).

Step 2 : Write out the slope of the line using the formula (refer to video below for the slope formula)

Step 3 : Derive the equation of the line from the above formula

The required equation is

Method 2

Step 1: Substitute m = – , x = –3 and y = 1 into the equation y = mx+ c to obtain the value of c.

Step 2: Write out the equation of the line

The required equation is or 2y = –3x – 7

The following video shows how to use the slope formula to calculate the slope of a linear equation given two points.

The following video shows another example of using method 1 to get the equation of a line.

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