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Quadratic Formula Calculator

Math Free Instant Private
Math

Solve quadratic equations ax^2 + bx + c = 0. Calculate discriminant, real or complex roots, vertex coordinates, and step-by-step solutions.

Reviewed by Miss Saima · MA Mathematics
Last updated:
Editorial Guidelines

⚙ Input Values

📊 Results

Discriminant (Δ = b² - 4ac)
1.0000
Root Type
Two Distinct Real Roots
First Root (x₁)
3.0000
Second Root (x₂)
2.0000
Vertex (h, k)
(2.50, -0.25)
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📐 Formula

Quadratic Formula: x = [-b ± √(b² - 4ac)] / (2a). Discriminant Δ = b² - 4ac. Vertex: h = -b/(2a), k = c - b²/(4a).

💡 Practical Example

✅

Solve x² - 5x + 6 = 0. Discriminant: (-5)² - 4(1)(6) = 25 - 24 = 1. Roots: x₁ =/2 = 3, x₂ = (5 - 1)/2 = 2. Vertex: (2.5, -0.25).

📖 About Quadratic Formula Calculator

A quadratic equation is a second-order polynomial equation of the form ax² + bx + c = 0, where a ≠

  • The discriminant Δ = b² - 4ac determines the nature of the roots:
  • If Δ > 0, the equation has two distinct real roots.
  • If Δ = 0, the equation has one repeated real root.
  • If Δ < 0, the equation has two complex conjugate roots.

To use the Quadratic Formula Calculator, enter your Coefficient a, Coefficient b (x), Constant c. The calculator instantly computes Discriminant, Root Type and more. Results update in real time as you change any input — no submit button needed.

How to Use This Calculator

Enter your Coefficient a (x²) (e.g. 1), Coefficient b (x) (e.g. -5), and Constant c (e.g. 6). Results update instantly as you type — adjust any value to compare scenarios.

The Formula

Quadratic Formula: x = [-b ± √(b² - 4ac)] / (2a). Discriminant Δ = b² - 4ac. Vertex: h = -b/(2a), k = c - b²/(4a).

Worked Example

Solve x² - 5x + 6 =

  • Discriminant: (-5)² - 4(1)(6) = 25 - 24 =
  • Roots: x₁ =/2 = 3, x₂ = (5 - 1)/2 =
  • Vertex: (2.5, -0.25).

Understanding Your Result

Evaluate your result in the context of your specific use case and relevant industry standards or reference values. A single calculated result is a starting point — test two to three scenarios to understand how sensitive the outcome is to your key input assumptions. For high-stakes decisions, verify your result against a secondary source or subject-matter expert before acting.

💡 Mathematical Rigor & Applied Context

  • This calculator applies exact mathematical definitions following conventions established by NIST and international standards bodies.
  • Rounding errors accumulate across multi-step calculations. For precision-critical work, maintain extra significant figures through all intermediate steps.
  • Many mathematical concepts have multiple valid formulations — if a result seems unexpected, verify which convention or definition applies to your context.
  • Dimensional analysis (unit tracking) is the fastest way to catch formula errors. Every term in an equation must have consistent, compatible units.
  • Numerical methods used in digital calculators introduce floating-point precision limits (~15 significant digits for IEEE 754 double precision).
  • For statistical and probabilistic calculations, always specify whether you are working with population parameters or sample statistics — formulas differ.
  • Visualizing a problem geometrically or testing with known boundary values (zero, infinity, negative) reveals hidden errors faster than algebraic checking.
  • When in doubt, validate your result against a simplified hand calculation or a published worked example from a textbook or standards document.

Results are for informational and educational purposes only. Always verify critical decisions with a qualified professional.

❓ Frequently Asked Questions

What is the discriminant of a quadratic equation?

The discriminant is Δ = b² - 4ac. It indicates the number and type of roots: positive means two real roots, zero means one real root, negative means two complex roots.

What is the vertex of a parabola?

The vertex is the peak or turning point of the parabola defined by y = ax² + bx + c. The x-coordinate is h = -b/(2a) and y-coordinate is k = f(h).

How precise are the results?

Results are calculated to 4 decimal places using standard mathematical formulas. For integer-only problems, results are shown as exact whole numbers.

Can I use this on my phone or tablet?

Yes. The calculator is fully responsive and works on all screen sizes including smartphones, tablets, and desktops.

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