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 (x_{1 }, y_{1} ) and has a slope of m then the point-slope form of the equation of the line is,
y - y_{1} = m ( x - x_{1} )
Sometimes it is written as,
y = y_{1} + m ( x - x_{1} )
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.