Mathematical Delta is the discriminant of quadratic equation in one variable.

Any unary quadratic equation can be matched. Because a≠0, we can know from the meaning of square root that the symbol can determine the root of a quadratic equation; It is called the discriminant of the root of a quadratic equation with one variable. It is expressed by "delta" (pronounced "delta"), that is, △ = b-4ac.

In the unary quadratic equation:

(1) when △ >; 0, the equation has two unequal real roots.

(2) When △=0, the equation has two equal real roots.

(3) When△

(4) 1 and 2 combination: When △≥0, the equation has real roots.