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)) / 2a

Where:

aCoefficient aCoefficient of x squared term
bCoefficient bCoefficient of x term
cConstant cThe constant term in the equation
xSolutionThe values of x that satisfy ax^2+bx+c=0

Step-by-Step Example

Here's how to calculate quadratic equations step by step:

  1. 1Identify a, b, c: Write the equation in standard form ax^2 + bx + c = 0.
  2. 2Calculate discriminant: Compute b^2 - 4ac to determine the number of solutions.
  3. 3Apply the formula: Plug a, b, c into the quadratic formula to find x.
  4. 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.

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Why 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.

Frequently Asked Questions