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.