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?
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Rearrange your equation into the form ax² + bx + c = 0.
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Enter the coefficients a, b, and c.
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Click Calculate to solve the equation.
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Check the equation, discriminant, solutions, and steps.
Key Features
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Solves any quadratic equation in standard form.
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Shows the constructed equation so you can verify your input.
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Displays the discriminant and the step-by-step working.
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Finds two real solutions, one repeated solution, or complex solutions.
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Accepts positive, negative, whole-number, and decimal coefficients.
Examples
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x² + 8x + 12 = 0 has solutions x₁ = -2 and x₂ = -6.
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x² - 8x + 12 = 0 has solutions x₁ = 2 and x₂ = 6.
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Rearranged from 2x² = x + 3, the equation 2x² - x - 3 = 0 gives x = 1.5 and x = -1.
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x² - 4x + 8 = 0 has complex solutions x = 2 ± 2i.
Common Use Cases
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Finding where a parabola crosses the x-axis.
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Solving second-degree equations in algebra and physics.
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Determining the dimensions in area and projectile problems.
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Checking the number and type of solutions from the discriminant.
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Verifying homework solutions with step-by-step working.
Tips & Best Practices
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Move all terms to one side so the equation equals zero before entering values.
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Expand any brackets and combine like terms first.
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Always check the constructed equation matches what you intended.
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Use the discriminant to predict two, one, or no real solutions.
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Remember the coefficient a cannot be zero.
Limitations
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The equation must be rearranged into standard form first.
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The coefficient a cannot be zero, or it is not quadratic.
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Solutions are rounded for readability.
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It solves second-degree equations only, not higher-degree ones.
Frequently Asked Questions
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What is standard form?
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Standard form is ax² + bx + c = 0, with all terms on one side and zero on the other.
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How do I rearrange an equation into standard form?
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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.
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What do x₁ and x₂ mean?
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They are the two solutions of the equation, the x-values where it equals zero and where its parabola crosses the x-axis.
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What if there are no real solutions?
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When the discriminant is negative, the parabola never crosses the x-axis and the solutions are complex, written with i.
Key Terminology
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Quadratic equation
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A second-degree equation of the form ax² + bx + c = 0 where a is not zero.
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Standard form
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A quadratic written with all terms on one side equal to zero.
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Solution (root)
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A value of x that makes the equation true.
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Discriminant
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The value b² - 4ac that reveals the number and type of solutions.
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Parabola
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The U-shaped curve of a quadratic function, whose x-intercepts are the solutions.