An integral equation that contains only one unknown (unary) and the highest order of the unknown is 2 (quadratic) is called unary quadratic equation. The univariate quadratic equation can be transformed into the general form ax+bx+c=0(a≠0) after sorting. Where ax is called quadratic term and a is the coefficient of quadratic term; Bx is called a linear term, and b is the coefficient of the linear term; C is called a constant term.

Introduce a quadratic equation with one variable;

(1) The meaning of the solution (root) of a quadratic equation with one variable: the value of the unknown quantity that can make the left and right sides of the quadratic equation with one variable equal is called the solution of the quadratic equation with one variable. Generally speaking, the solution of a quadratic equation is also called the root of a quadratic equation (the solution of an equation with only one unknown is also called the root of this equation).

(2) According to the basic theorem of algebra, a quadratic equation with one variable has only two roots (multiple roots are calculated by multiple numbers), and the case of the roots is determined by the discriminant (△ = b? -4ac) decision.