Question

用配方法解一元二次方程X平方+PX+|Q

Answer 1

X^2+PX+Q

=X^2+2*P/2X+(P/2)^2-(P/2)^2+Q

=(X+P/2)^X-P^2/4+Q

=0

所以: (X+P/2)^X=P^2/4-Q

X=-P/2±√（P^2/4-Q）

=[-P±√（P^2-4Q）]/2