The next special form of the line which we have to look at is the point-slope form of the line. This form is extremely useful for writing the equation of any line. If we know that a line passes through the point (x1 , y1 ) and has a slope of m then the point-slope form of the equation of the line is,
y - y1 = m ( x - x1 )
Sometimes it is written as,
y = y1 + m ( x - x1 )
As stated earlier this form is specifically useful for writing down the equation of a line so let's take a look at an example of this.