Calculation: △ = b 2-4 * a * c (A, B and C are the coefficients of the quadratic term, linear term and constant term of the equation respectively) Function: An example of judging the existence of real roots in a quadratic equation with one variable;
1、x^2+2x+3=0 △=2^2-4* 1*3=-8<； The 0 equation has no real root.
2. Does the equation x2+2x+1= 0 △ = 2 2-4 *1*1= 0 have two equal real roots?
3、x^2+2x- 1=0 △=2^2-4* 1*(- 1)=8>； The 0 equation has two unequal real roots.
Extended data:
Application of discriminant of quadratic equation in one variable
(1) Solve the equation and judge the root of a quadratic equation.
It has two different types:
① The coefficients are all numbers;
② The coefficient contains letters;
③ The letters in the coefficient artificially give certain conditions.
(2) According to the root of a quadratic equation, determine the value range of letters in the equation or the relationship between letters.
(3) Discriminant is used to prove the roots of the equation (there are real roots, no real roots, two unequal real roots and two equal real roots).