First, the formula method.

Second, the matching method.

Third, direct Kaiping method.

Fourth, factorization.

Formula method 1 first judge △=b_-4ac, if△

2 If △=0, the original equation has two identical solutions: x =-b/(2a);

3 if △ > 0, the solution of the original equation is: x =((-b)√(△)/(2a).

Matching method. First, the constant c is moved to the right of the equation: ax _+bx =-C. If the quadratic term is converted into 1, X_+(b/a)X=-c/a, and the square of half of (b/a) is added to both sides of the equation, x _+(b/a) x+(b

5① If-c/a+(b/(2a)) _

② If -c/a+(b/(2a))_=0, the original equation has two identical solutions: x =-b/(2a);

③If-c/a+(b/(2a))_ & gt； 0, the solution of the original equation is x = (-b) √ ((b _-4ac))/(2a).