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Online Quadratic Equation Calculator

Online Quadratic Equation Calculator

Solve any quadratic equation ax² + bx + c = 0 and get the two solutions, the discriminant, and step-by-step working.

Equation 1x2 + 8x + 12 = 0
Solution x = -2 or -6

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What Is This Tool?

The Quadratic Equation Calculator solves second-degree equations written in standard form, ax² + bx + c = 0. Enter the coefficients a, b, and c, and it shows the equation it built, the discriminant, and the solutions x₁ and x₂, along with the steps. The solutions are the x-values where the equation equals zero — the points where its parabola crosses the x-axis.

How to Use This Tool?

  • Rearrange your equation into the form ax² + bx + c = 0.
  • Enter the coefficients a, b, and c.
  • Click Calculate to solve the equation.
  • Check the equation, discriminant, solutions, and steps.

Key Features

  • Solves any quadratic equation in standard form.
  • Shows the constructed equation so you can verify your input.
  • Displays the discriminant and the step-by-step working.
  • Finds two real solutions, one repeated solution, or complex solutions.
  • Accepts positive, negative, whole-number, and decimal coefficients.

Examples

  • x² + 8x + 12 = 0 has solutions x₁ = -2 and x₂ = -6.
  • x² - 8x + 12 = 0 has solutions x₁ = 2 and x₂ = 6.
  • Rearranged from 2x² = x + 3, the equation 2x² - x - 3 = 0 gives x = 1.5 and x = -1.
  • x² - 4x + 8 = 0 has complex solutions x = 2 ± 2i.

Common Use Cases

  • Finding where a parabola crosses the x-axis.
  • Solving second-degree equations in algebra and physics.
  • Determining the dimensions in area and projectile problems.
  • Checking the number and type of solutions from the discriminant.
  • Verifying homework solutions with step-by-step working.

Tips & Best Practices

  • Move all terms to one side so the equation equals zero before entering values.
  • Expand any brackets and combine like terms first.
  • Always check the constructed equation matches what you intended.
  • Use the discriminant to predict two, one, or no real solutions.
  • Remember the coefficient a cannot be zero.

Limitations

  • The equation must be rearranged into standard form first.
  • The coefficient a cannot be zero, or it is not quadratic.
  • Solutions are rounded for readability.
  • It solves second-degree equations only, not higher-degree ones.

Frequently Asked Questions

What is standard form?
Standard form is ax² + bx + c = 0, with all terms on one side and zero on the other.

How do I rearrange an equation into standard form?
Move every term to one side so the other side is zero, expand any brackets, and combine like terms. For example, 2x² = x + 3 becomes 2x² - x - 3 = 0.

What do x₁ and x₂ mean?
They are the two solutions of the equation, the x-values where it equals zero and where its parabola crosses the x-axis.

What if there are no real solutions?
When the discriminant is negative, the parabola never crosses the x-axis and the solutions are complex, written with i.

Key Terminology

Quadratic equation
A second-degree equation of the form ax² + bx + c = 0 where a is not zero.
Standard form
A quadratic written with all terms on one side equal to zero.
Solution (root)
A value of x that makes the equation true.
Discriminant
The value b² - 4ac that reveals the number and type of solutions.
Parabola
The U-shaped curve of a quadratic function, whose x-intercepts are the solutions.

Quick Knowledge Check

What is the standard form of a quadratic equation?
At most, how many solutions can a quadratic equation have?
The solutions of a quadratic equation are where its parabola meets the: