A complete square form is obtained by matching method on the left side of the equation, and the sorted constants are on the right side of the equation.

Then square both sides of the equation to get the result.

Such as: ax? +bx+c=0

x？ +bx/a+c/a=0

x？ +bx/a+(b/2a)？ +c/a=(b/2a)？

(x+b/2a)？ =(b/2a)？ -c/a=(b？ -4ac)/4a？

Prescription: x+b/2a = (√ b? -4ac)/2a

So: x =-b/2a (√ b? -4ac)/2a=[-b (√b？ -4ac)]/2a