Discriminant Calculator - Quadratic Discriminant Calculator & Root Analysis
Free discriminant calculator for quadratic equations. Calculate discriminant, analyze root types, and determine parabola intersection behavior. Our calculator uses the discriminant formula Δ = b² - 4ac to determine the nature and number of roots for any quadratic equation.
Last updated: December 15, 2024
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Quadratic Equation
Coefficient of x²
Coefficient of x
Constant term
Discriminant Analysis
Discriminant (Δ = b² - 4ac)
1
Root Type:
Two distinct real roots
Number of Roots:
2
Roots:
x₍1₎ = 3
x₍2₎ = 2
Graph Behavior:
Parabola intersects x-axis at two distinct points
Analysis:
The quadratic equation has two distinct real solutions
Factorization:
Can be factored into linear terms
Discriminant Rules:
- • Δ > 0: Two distinct real roots (parabola crosses x-axis twice)
- • Δ = 0: One repeated real root (parabola touches x-axis once)
- • Δ < 0: Two complex roots (parabola doesn't touch x-axis)
- • Formula: Δ = b² - 4ac
Discriminant Calculator Types & Analysis Methods
Formula
Δ = b² - 4ac
Determines root types for ax² + bx + c = 0
Classifications
Real, Repeated, Complex
Analyzes Δ > 0, Δ = 0, and Δ < 0 cases
Intersections
0, 1, or 2 points
Visual representation of quadratic graph behavior
Factorability
Perfect Square Test
Checks if discriminant is a perfect square
Complex form
a ± bi
Handles imaginary solutions when Δ < 0
Full formula
x = (-b ± √Δ) / 2a
Discriminant as part of complete solution process
Quick Example Result
For quadratic equation x² - 5x + 6 = 0:
Discriminant (Δ)
1
Root Type
Two distinct real roots
How Our Discriminant Calculator Works
Our discriminant calculator analyzes quadratic equations using the discriminant formula Δ = b² - 4ac to determine root types and parabola behavior. The calculation applies fundamental algebraic principles to classify solutions and provide insights into quadratic function properties.
The Discriminant Formula
Δ = b² - 4acΔ > 0
Two distinct real roots
Parabola crosses x-axis twice
Δ = 0
One repeated real root
Parabola touches x-axis once
Δ < 0
Two complex roots
Parabola doesn't touch x-axis
Shows three cases of parabola behavior based on discriminant value
Mathematical Foundation
The discriminant is derived from the quadratic formula and reveals the nature of solutions before actually computing them. It's the expression under the square root in the quadratic formula, making it a powerful tool for analysis without full calculation.
- Positive discriminant indicates real, distinct roots
- Zero discriminant means a perfect square trinomial
- Negative discriminant produces complex conjugate pairs
- Perfect square discriminants allow rational factorization
- Discriminant magnitude affects root separation
- Sign determines parabola's relationship with x-axis
Sources & References
- Algebra and Trigonometry - Stewart, Redlin, Watson (4th Edition)Comprehensive coverage of quadratic equations and discriminant analysis
- College Algebra - Blitzer (7th Edition)Detailed treatment of quadratic functions and their properties
- Purple Math - Discriminant and Quadratic FormulaEducational resources for understanding discriminant concepts
Need help with other algebra calculations? Check out our quadratic formula calculator and partial fractions calculator.
Get Custom Calculator for Your PlatformDiscriminant Calculator Examples
Given Equation:
- Equation: 2x² - 7x + 3 = 0
- a: 2
- b: -7
- c: 3
Discriminant Calculation:
- Apply formula: Δ = b² - 4ac
- Substitute: Δ = (-7)² - 4(2)(3)
- Calculate: Δ = 49 - 24
- Result: Δ = 25
Result: Δ = 25 > 0 (Two distinct real roots)
Since 25 is a perfect square, the roots are rational: x = 3 and x = 1/2
Perfect Square Example
x² - 6x + 9 = 0
Δ = 0 (One repeated root: x = 3)
Complex Roots Example
x² + x + 1 = 0
Δ = -3 < 0 (Two complex roots)
Frequently Asked Questions
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