Quadratic Formula Calculator
Solve ax² + bx + c = 0 with roots, discriminant, vertex, and step-by-step results.
What is the Quadratic Formula?
The quadratic formula is a universal method for solving any quadratic equation of the form ax² + bx + c = 0, where a, b, and c are real numbers and a ≠ 0. The formula x = (-b ± √(b² - 4ac)) / 2a gives the exact roots of the equation. The expression under the square root, b² - 4ac, is called the discriminant and determines the nature and number of the roots.
Understanding the Discriminant
The discriminant (D = b² - 4ac) tells you everything about the roots without actually solving the equation. When D > 0, the equation has two distinct real roots. When D = 0, it has exactly one repeated real root. When D < 0, the equation has two complex conjugate roots expressed in the form a ± bi. Understanding the discriminant is key to predicting the behavior of quadratic functions.
The Vertex of a Parabola
Every quadratic equation corresponds to a parabola on a graph. The vertex is the highest or lowest point of the parabola, located at x = -b / 2a. The y-coordinate of the vertex is found by substituting this x value back into the equation. If a > 0, the parabola opens upward and the vertex is a minimum; if a < 0, it opens downward and the vertex is a maximum.