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Quadratic Equation Solver

Solve equations in the form: ax² + bx + c = 0

ax² + bx + c = 0
The coefficient of x² (must be non-zero)
The coefficient of x
The constant term
Example: For 2x² - 5x + 3 = 0
a = 2, b = -5, c = 3

Results

Discriminant (Δ)
-
Root Type:
-
Root 1 (x₁):
-
Root 2 (x₂):
-
Vertex (h, k):
-
Axis of Symmetry:
-

Quadratic Formula & Concepts

The Quadratic Formula

x = [-b ± √(b² - 4ac)] / 2a

This formula finds the values of x where ax² + bx + c = 0

What is the Discriminant?

Δ = b² - 4ac

The discriminant (Δ) tells us about the nature of the roots:

  • Δ > 0: Two distinct real roots
  • Δ = 0: One repeated real root (double root)
  • Δ < 0: Two complex conjugate roots (no real solutions)

Vertex of a Parabola

h = -b / 2a k = c - (b² / 4a) Vertex = (h, k)

Axis of Symmetry

x = -b / 2a

This is the vertical line around which the parabola is symmetric.

Key Concepts

  • Quadratic Equation: An equation of degree 2 in the form ax² + bx + c = 0
  • Root/Zero: A value of x that makes the equation equal to zero
  • Parabola: The graph of a quadratic function (U-shaped)
  • Real Roots: Roots that are real numbers (not complex)
  • Complex Roots: Roots that contain imaginary numbers (involve √-1)
  • Vertex: The highest or lowest point of the parabola

How to Use the Calculator

1 Enter Coefficient a
Enter the coefficient of the x² term. This cannot be zero (or it's not a quadratic equation).
2 Enter Coefficient b
Enter the coefficient of the x term. This can be any number (positive, negative, or zero).
3 Enter Coefficient c
Enter the constant term. This can be any number.
4 Click Solve
Click the "Solve" button to calculate the roots and other properties.
5 View Results
The calculator will display the discriminant, root type, both roots, vertex, and axis of symmetry.

Understanding Your Results

  • Discriminant: Shows the value of b² - 4ac
  • Root Type: Tells you if roots are real or complex
  • Root 1 & Root 2: The solutions to your equation
  • Vertex: The turning point of the parabola
  • Axis of Symmetry: The line where the parabola mirrors itself

Understanding Quadratic Equations

What is a Quadratic Equation?

A quadratic equation is a polynomial equation of degree 2. It has the standard form ax² + bx + c = 0, where a, b, and c are constants and a ≠ 0.

Real-World Applications

  • Physics: Projectile motion, falling objects, and trajectory calculations
  • Engineering: Structural analysis and design problems
  • Economics: Profit and loss calculations, cost optimization
  • Business: Revenue and pricing models
  • Medicine: Drug concentration and dosage calculations
  • Construction: Area calculations and design parameters

Example Problems

  • Problem: x² - 5x + 6 = 0
    Solution: a = 1, b = -5, c = 6 → x = 2 or x = 3
  • Problem: 2x² - 4x + 2 = 0
    Solution: a = 2, b = -4, c = 2 → x = 1 (double root)
  • Problem: x² + 2x + 5 = 0
    Solution: a = 1, b = 2, c = 5 → Complex roots (no real solutions)
Tip: If the discriminant is negative, there are no real solutions, but there are two complex conjugate solutions!

Frequently Asked Questions

Can a be zero?

No, a cannot be zero. If a = 0, the equation becomes linear (bx + c = 0), not quadratic. You must have a ≠ 0.

What if the discriminant is negative?

A negative discriminant means there are no real solutions, only complex roots. The parabola doesn't cross the x-axis.

What is a double root?

A double root occurs when the discriminant equals zero. Both roots are the same value. The parabola touches the x-axis at exactly one point.

How do I find the vertex?

The x-coordinate of the vertex is h = -b/2a. Substitute this into the equation to find the y-coordinate (k).

What's the axis of symmetry?

It's a vertical line at x = -b/2a. The parabola is symmetric (mirrored) about this line.

How do I factor a quadratic?

Factoring writes the equation as a(x - r₁)(x - r₂) = 0, where r₁ and r₂ are the roots. You can find the roots using the quadratic formula.

What if I get complex roots?

Complex roots have imaginary parts (involving i = √-1). This means the parabola doesn't cross the real x-axis.

Can b or c be zero?

Yes! Both b and c can be zero. You can have equations like x² - 4 = 0 or x² - 5x = 0. Only a cannot be zero.

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