Various Equation Forms of a Straight Line
by
Larry E. Dodd
 www.101science.com

 

The equation of a straight line can be written in three different forms. Below are three equation forms and proof they are all equal to each other.

y – y₁ = m(x - x₁)        :: Point slope equation form. 
                                    Where m=slope and y – y₁ and  x - x₁ are points on the line
y = mx + b                :: Slope Intercept form.    
                                     Where m=slope, b=y interecpt when x=0
Ax + By = C               :: Standard form.

Example:

Lets take the straight line that crosses two (x, y) points of (3,2) and (8,4). The equations for this line are shown below.  All three forms of the equation represent the same straight line shown in the graph.

y - 2 = 2/5(x-3) :: Point slope form
y = 2/5x + .8     :: Slope intercept form
2x - 5y = - 4      :: Standard form

 

 

 

 

 

 

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