A quadratic equation in the variable x is an equation of the form ax² + bx + c = 0, where a, b, c are real numbers, a ≠ 0.
For example, 2x² + x – 300 = 0 is a quadratic equation.
The uncertainty of ‘probably’ etc can be measured numerically by means of ‘probability’ in many cases.
So, x² + 4x – 5 = 0 can be written as (x + 2)² – 9 = 0 by this process of completing the square. This is known as the method of completing the square.Quadratic Formula
Thus, if b² – 4ac ≥ 0, then the roots of the quadratic equation ax² + bx + c = 0 are given by This formula for finding the roots of a quadratic equation is known as the quadratic formula.Discrimination of Quadratic Equation
b² – 4ac determines whether the quadratic equation ax² + bx + c = 0 has real roots or not, b² – 4ac is called the discriminant of this quadratic equation.
So, a quadratic equation ax² + bx + c = 0 has
(i) two distinct real roots, if b² – 4ac > 0,
(ii) two equal real roots, if b² – 4ac = 0,
(iii) no real roots, if b² – 4ac < 0.