Find the equation of the line that passes through the point whose coordinates are

slope  =  [y₂ - y₁] / [x₂ - x₁]

 

Using the points  (-1, -3)  and  (x, y)  and a slope of  -3 , we have

 

-3  =  [y - -3] / [x - -1]

 

-3  =  [y + 3] / [x + 1]           To get this into slope-intercept form, multiply both sides by  x + 1 .

 

-3[ x + 1 ]  =  y + 3

 

-3x - 3  =  y + 3                   Subtract  3  from both sides of the equation.

 

-3x - 6  =  y

 

y  =  -3x - 6