LogoPractical Web Tools

Free Forever

All our tools are completely free to use. No account required, No hidden fees and No subscriptions.

Fast & Secure

All processing happens in your browser. Your files never leave your device.

No File Size Limits

Convert files of any size. No restrictions on file sizes or number of conversions.

Batch Processing

Convert multiple files at once to save time and effort.

File Converters

  • PDF Tools
  • Image Converter
  • Video Converter
  • Audio Converter
  • Document Converter
  • eBook Converter
  • Archive Tools
  • File Tools

Calculators

  • Finance Calculators
  • Health Calculators
  • Math Calculators
  • Science Calculators
  • Other Tools

Popular Tools

  • PDF to Word
  • HEIC to JPG
  • Merge PDF
  • Fillable PDF Creator
  • Mortgage Calculator
  • BMI Calculator
  • AI Chat

Company

  • About Us
  • Blog
  • Contact
  • Request a Tool

Legal

  • Privacy Policy
  • Terms of Service
Email Support
Practical Web Tools Logo
Practical Web Tools

Free Tools — Your Files Never Leave Your Device

Practical Web Tools - Convert files & chat with AI — fully offline | Product Hunt

© 2026 Opal Emporium LLC. All rights reserved.

Privacy-first file conversion and AI chat. No accounts, no uploads, no tracking.

  1. Home
  2. Math Calculators
  3. Quadratic Formula Calculator

Quadratic Formula Calculator

Solve quadratic equations ax² + bx + c = 0 using the quadratic formula. Find roots, discriminant, vertex, and view the parabola graph with step-by-step solution.

Formula:x = (-b ± √(b²-4ac)) / 2a

Solutions

Roots

3, 2

Two real roots

Discriminant1
Vertex(2.5, -0.25)
Y-Intercept6

Try These Examples

Common quadratic equations

Enter Coefficients

For the equation ax² + bx + c = 0

Your equation:

x² - 5x + 6 = 0

Parabola Graph

Opens upward (∪)Axis: x = 2.5

Solutions (Roots)

First Root (x₁)

3

Second Root (x₂)

2

Factored Form

(x -3)(x -2) = 0

Parabola Properties

Discriminant

1

b² - 4ac

Vertex

(2.5, -0.25)

Minimum point

Axis of Symmetry

x = 2.5

-b / (2a)

Y-Intercept

(0, 6)

Where x = 0

Step-by-Step Solution

1. Identify coefficients:

a = 1, b = -5, c = 6

2. Calculate the discriminant (b² - 4ac):

Δ = (-5)² - 4(1)(6)

Δ = 25 - 24

Δ = 1

Since Δ > 0, there are two distinct real roots

3. Apply the quadratic formula:

x = (-b ± √Δ) / (2a)

x = (-(-5) ± √1) / (2 × 1)

x = (5 ± 1) / 2

4. Solutions:

x = 3, 2

Quadratic Formula

Interactive formula breakdown

a-var="x">x = (-b ± √(b²-4ac)) / 2a
x
Solution

The values that satisfy the equation

Current value: x = 3, 2
a
Quadratic coefficient

Coefficient of x² term

Current value: 1
b
Linear coefficient

Coefficient of x term

Current value: -5
c
Constant term

The constant value

Current value: 6
Δ
Discriminant

b² - 4ac, determines root type

Current value: 1

Practice Quadratic Problems

Test your understanding of quadratic equations

Practice with 6 problems to test your understanding.

Solutions

Roots

3, 2

Two real roots

Discriminant1
Vertex(2.5, -0.25)
Y-Intercept6

?How to Use the Quadratic Formula

The quadratic formula x = (-b +/- sqrt(b^2-4ac)) / 2a solves any quadratic equation ax^2 + bx + c = 0. The discriminant (b^2-4ac) determines the nature of roots: if positive, two real roots exist; if zero, one repeated root; if negative, two complex conjugate roots. The vertex is at x = -b/(2a), and the parabola opens up when a > 0.

What is a Quadratic Equation?

A quadratic equation is a polynomial equation of degree 2 in the form ax^2 + bx + c = 0, where a is not equal to 0. The quadratic formula provides a method to find the values of x (called roots or solutions) that make the equation true. These roots represent the x-intercepts of the corresponding parabola on a graph.

Key Facts About Quadratic Equations

  • Quadratic formula: x = (-b +/- sqrt(b^2-4ac)) / 2a
  • Discriminant (b^2-4ac) determines root type: positive = 2 real, zero = 1 real, negative = 2 complex
  • Vertex of parabola is at x = -b/(2a), which is the axis of symmetry
  • Parabola opens upward when a > 0 (minimum at vertex), downward when a < 0 (maximum)
  • Y-intercept is always the constant term c (where x = 0)
  • Complex roots always come in conjugate pairs: a + bi and a - bi
  • Factored form exists when roots are rational: (x - r1)(x - r2) = 0
  • Sum of roots = -b/a and product of roots = c/a (Vieta's formulas)

Quick Answer

The quadratic formula x = (-b +/- sqrt(b^2-4ac)) / 2a solves any quadratic equation ax^2 + bx + c = 0. The discriminant (b^2-4ac) determines the nature of roots: if positive, two real roots exist; if zero, one repeated root; if negative, two complex conjugate roots. The vertex is at x = -b/(2a), and the parabola opens up when a > 0.

Frequently Asked Questions

The quadratic formula x = (-b ± √(b²-4ac)) / 2a solves any quadratic equation ax² + bx + c = 0. It gives the x-values where the parabola crosses the x-axis (the roots or solutions).

x = (-b ± √(b²-4ac)) / 2a. It finds the roots of any quadratic equation ax² + bx + c = 0.

The discriminant (b² - 4ac) determines the nature of the roots. If positive, there are two distinct real roots. If zero, there is one repeated real root. If negative, there are two complex conjugate roots.

b² - 4ac determines root type: positive = 2 real, zero = 1 real, negative = 2 complex.

The vertex is the turning point of the parabola - its highest or lowest point. For y = ax² + bx + c, the vertex is at x = -b/(2a), and the y-coordinate is found by substituting this x value.

The parabola's turning point. Located at x = -b/(2a). It's a maximum if a < 0, minimum if a > 0.

The axis of symmetry is the vertical line that divides the parabola into two mirror images. It passes through the vertex and has the equation x = -b/(2a).

A vertical line through the vertex (x = -b/2a) that divides the parabola into mirror halves.

A parabola opens upward (∪ shape) when a > 0, with a minimum at the vertex. It opens downward (∩ shape) when a < 0, with a maximum at the vertex.

Opens up (minimum) when a > 0. Opens down (maximum) when a < 0.

Complex roots occur when the discriminant is negative. They involve the imaginary unit i (where i² = -1) and always come in conjugate pairs like a + bi and a - bi. The parabola doesn't cross the x-axis.

Roots with imaginary numbers (i). They occur when discriminant < 0 and the parabola doesn't cross x-axis.

Last updated: 2025-01-15

Solutions

Roots

3, 2

Two real roots

Discriminant1
Vertex(2.5, -0.25)
Y-Intercept6