Atechnique used to rewrite a quadratic function in standard form to vertex form is

The vertex form of a quadratic function is given by
                                      
where (h,k) is the vertex of parabola. In some literatures, the standard form of the quadratic equation is written as 
                                      
Therefore, in order to avoid the confusion, the first equation is taken as a vertex form. When the standard form is converted into the vertex form, the process is called completing the square.