Useful expansions form quadratic equation(with negative signs)

   in special form

The left hand side comes from a root of quadratic functionthough it means 1=0. Here, we can regard a=1, b=-x, and c=1 as in . Recall that the roots are . The right hand side is derived from

   in special form

The left hand side comes from a root of quadratic function  though it is . Since , we can regard a=1, b=-1, and c=x as in . The right hand side is derived from

   in special form

The left hand side comes from a root of quadratic function  though it is . Since , we can regard a=1, b=-x, and c=x as in . The right hand side is derived from