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Quadratic Equation Solver

Free online quadratic equation solver. No sign-up, no installation. Runs entirely in your browser.

Input Coefficients

Equation: a·x² + b·x + c = 0





What is a Quadratic Equation?

A quadratic equation is a polynomial equation of the second degree, written in the standard form ax² + bx + c = 0, where a, b, and c are constants and a ≠ 0.

Quadratic equations appear in many real-world applications including physics (projectile motion), engineering, economics, and geometry. Solutions to these equations are called roots or zeros.

How to Use This Solver

  1. Enter the coefficients: Input values for a, b, and c in the input fields above.
  2. Click Solve: Press the “Solve Equation” button to calculate the roots and analysis.
  3. Review the solution: The tool displays the discriminant, root type, vertex coordinates, exact roots, and step-by-step working.
  4. View the graph: A visual representation of the parabola is drawn with roots marked on the x-axis.
  5. Copy results: Click on any output section to copy to clipboard.

Common Use Cases

  • Physics: Solving projectile motion problems and calculating trajectory paths.
  • Engineering: Designing parabolic structures, antennas, and reflectors.
  • Finance: Modeling profit/loss functions and break-even analysis.
  • Education: Learning algebra and understanding quadratic functions in high school mathematics.
  • Optimization: Finding minimum or maximum values in various applications.

Frequently Asked Questions

What is the discriminant?

The discriminant (Δ) is b² – 4ac. It determines the nature of the roots: if Δ > 0, there are two distinct real roots; if Δ = 0, there is one repeated real root; if Δ < 0, there are two complex conjugate roots.

What is the quadratic formula?

The quadratic formula is x = (-b ± √Δ) / (2a), where Δ = b² – 4ac. This formula always gives the exact solutions to any quadratic equation.

What is the vertex of a parabola?

The vertex is the highest or lowest point on the parabola. For a quadratic function f(x) = ax² + bx + c, the vertex is at h = -b/(2a) and k = f(h).

Can this solver handle complex roots?

Yes! When the discriminant is negative, the roots are complex numbers in the form a + bi. The solver displays both the real and imaginary parts clearly.

What is the axis of symmetry?

The axis of symmetry is a vertical line that divides the parabola into two mirror images. Its equation is x = -b/(2a), which is the same as the x-coordinate of the vertex.

Why must coefficient a be non-zero?

If a = 0, the equation becomes bx + c = 0, which is linear, not quadratic. The quadratic formula and discriminant are only valid when the highest degree term (x²) has a non-zero coefficient.


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