How to Calculate Quadratic Equations
The quadratic formula solves any equation of the form ax^2 + bx + c = 0. It always works, even when factoring is difficult or impossible.
The Formula
x = (-b +/- sqrt(b^2 - 4ac)) / 2aWhere:
aCoefficient a — Coefficient of x squared termbCoefficient b — Coefficient of x termcConstant c — The constant term in the equationxSolution — The values of x that satisfy ax^2+bx+c=0Step-by-Step Example
Here's how to calculate quadratic equations step by step:
- 1Identify a, b, c: Write the equation in standard form ax^2 + bx + c = 0.
- 2Calculate discriminant: Compute b^2 - 4ac to determine the number of solutions.
- 3Apply the formula: Plug a, b, c into the quadratic formula to find x.
- 4Simplify: Reduce fractions and simplify radicals in your answer.
Following these 4 steps gives you the final quadratic equations value.
Skip the Math
A ball thrown upward at 20 m/s from 1.5m height follows h = -4.9t^2 + 20t + 1.5; the quadratic formula finds when it hits the ground.
Use the Free CalculatorWhy You Need This Calculation
- Quadratic equations model projectile motion, profit optimization, area problems, and many physics scenarios.
Common Mistakes
Forgetting the +/- gives two solutions.
Always compute both the plus and minus roots.
Dropping the negative sign on b.
The formula starts with -b, not b.
Ignoring a negative discriminant.
A negative discriminant means no real solutions exist.