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Quadratic Formula Calculator

Solve Quadratic Equation

Enter coefficients a, b, and c for ax² + bx + c = 0

1x2 + 0x + 0 = 0

Enter coefficients a, b, and c to solve the quadratic equation.

Results & Actions

Calculate and view quadratic solutions

Discriminant (Δ)
0
Perfect square
Root 1 (x₁)
0
Root 2 (x₂)
0
Root Type
Real & equal

Step-by-Step Solution

  1. Equation: 1x² + 0x + 0 = 0
  2. Discriminant: Δ = b² - 4ac = 0² - 4×1×0 = 0
  3. Δ = 0: One real repeated root
  4. Root: x = -b / 2a = 0 / 2 = 0

Parabola Visualization

Your browser does not support the canvas element. Graph shows a parabola opening upward with vertex at (0,0).

Vertex: (0, 0)

Axis: x = 0

Direction: Upward

How It Works

Enter coefficients a, b, and c to solve ax² + bx + c = 0. The calculator computes discriminant, determines root type, and provides exact solutions with step-by-step explanations.

Root Types

Based on discriminant value: Δ > 0 gives two real roots, Δ = 0 gives one real repeated root, Δ < 0 gives complex conjugate roots with imaginary components.

Real Applications

Used in physics for projectile motion, engineering for optimization problems, architecture for parabolic designs, economics for profit maximization, and computer graphics.

Quadratic Formula & Equations

Standard Form

ax² + bx + c = 0
a ≠ 0, where a, b, and c are real number coefficients

Quadratic Formula

x = [-b ± √(b² - 4ac)] / 2a
± indicates two possible solutions, √ denotes square root

Discriminant

Δ = b² - 4ac
Δ > 0: Two real roots, Δ = 0: One real root, Δ < 0: Complex roots

Step-by-Step Examples

Projectile Motion

-4.9t² + 20t + 1 = 0
Δ = 20² - 4(-4.9)(1) = 419.6
t = [-20 ± √419.6] / -9.8
Roots: t = 0.05s and t = 4.13s

Area Optimization

x² - 12x + 35 = 0
Δ = (-12)² - 4(1)(35) = 4
x = [12 ± √4] / 2
Roots: x = 7 and x = 5

Complex Roots

x² + 2x + 5 = 0
Δ = 2² - 4(1)(5) = -16
x = [-2 ± √(-16)] / 2
Roots: -1 ± 2i

Understanding Quadratic Equations

Quadratic equations are polynomial equations of degree 2 that describe parabolic relationships in mathematics, physics, engineering, and many other fields. The graph of a quadratic equation is always a parabola, which can open upward or downward depending on the coefficient 'a'.

What is a Quadratic Equation?

A quadratic equation is any equation that can be rearranged in standard form as ax² + bx + c = 0, where x represents an unknown variable, and a, b, and c represent known numbers with a ≠ 0. The solutions to these equations are called roots or zeros of the equation.

The Discriminant: Key to Understanding Roots

The discriminant (Δ = b² - 4ac) determines the nature of the roots without actually calculating them:

  • Δ > 0: Two distinct real roots - the parabola crosses the x-axis at two different points
  • Δ = 0: One real repeated root - the parabola touches the x-axis at exactly one point (the vertex)
  • Δ < 0: Two complex conjugate roots - the parabola doesn't intersect the x-axis at any real points

Practical Applications

Quadratic equations model numerous real-world phenomena:

Physics: Projectile Motion

The height h of a projectile at time t is given by: h(t) = -½gt² + v₀t + h₀

Solving h(t) = 0 gives the times when the projectile is at ground level. For example, a ball thrown upward from 1 meter with initial velocity 20 m/s under gravity (g = 9.8 m/s²) follows: -4.9t² + 20t + 1 = 0

The solutions t = 0.05s and t = 4.13s represent when the ball passes through height 1 meter on its way up and down.

Geometry: Area Optimization

If a rectangle has area 35 square units and perimeter 24 units, its dimensions satisfy: x² - 12x + 35 = 0

The solutions x = 7 and x = 5 give the rectangle's dimensions. This demonstrates how quadratic equations solve optimization problems where you maximize or minimize quantities under constraints.

How to Interpret the Results

Real Roots: Represent actual x-intercepts where the parabola crosses the x-axis. These are the solutions that make the equation true.

Complex Roots: Indicate the parabola doesn't intersect the x-axis. In practical terms, this means no real number satisfies the equation, which can occur in systems that don't reach certain states.

Vertex: The turning point of the parabola (minimum if a > 0, maximum if a < 0). Calculated at x = -b/(2a), this point represents optimal values in optimization problems.

Frequently Asked Questions

What if coefficient a equals zero?
If a=0, the equation becomes linear (bx + c = 0), not quadratic. Our calculator requires a ≠ 0 for valid quadratic solutions.
How accurate are the decimal approximations?
Roots display to 3 decimal places by default. For exact radical forms, manual simplification may be needed beyond calculator display limits.
Can the calculator handle fractions or irrational coefficients?
Yes, enter fractions as decimals (e.g., 1/2 as 0.5). The calculator processes any real number coefficients, including π or √2 approximations.
What do complex roots mean in practical applications?
Complex roots indicate no real x-intercepts. In physics, this might mean a projectile never reaches a certain height; in business, no break-even point exists.
How do I interpret a double root (Δ=0)?
A double root means the parabola touches but doesn't cross the x-axis. The vertex lies exactly on the axis, indicating an optimal minimum or maximum value.
Can this calculator solve quadratic equations in other forms?
Convert to standard form first. For vertex form a(x-h)² + k = 0, expand to ax² - 2ahx + ah² + k = 0 before entering coefficients.

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