Quadratic Equation: ax² + bx + c = 0
Roots: x = (-b ± √(b²-4ac))/(2a). Discriminant Δ = b²-4ac: Δ>0 two real roots, Δ=0 one double root, Δ<0 two complex roots. Vertex at x = -b/(2a).
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Δ>0: two distinct real roots. Δ=0: one repeated root. Δ<0: two complex conjugates. Vertex at axis of symmetry. Sum of roots = -b/a, product = c/a (Vieta).
Ready to run the numbers?
Why: Quadratics model projectiles, profit, area. Discriminant tells root type. Vertex gives max/min. Completing the square or formula yields roots.
How: Compute Δ = b²-4ac. If Δ≥0: x = (-b±√Δ)/(2a). If Δ<0: complex roots with ±i√|Δ|. Vertex: x = -b/(2a), y = f(x).
Run the calculator when you are ready.
Coefficients (ax² + bx + c = 0)
Discriminant & Vertex
Solution Type
📐 Step-by-Step Breakdown
For educational and informational purposes only. Verify with a qualified professional.
🧮 Fascinating Math Facts
x = (-b±√(b²-4ac))/(2a)
— Quadratic formula
Δ = b²-4ac determines root type
— Discriminant
📋 Key Takeaways
- • Quadratic formula: x = (-b ± √(b² - 4ac)) / (2a)
- • Discriminant Δ = b² - 4ac determines solution type
- • Δ > 0: two real roots; Δ = 0: one repeated root; Δ < 0: complex conjugate roots
- • Vertex at x = -b/(2a); axis of symmetry is vertical through vertex
💡 Did You Know?
📖 How It Works
For ax² + bx + c = 0, compute Δ = b² - 4ac. If Δ ≥ 0, use x = (-b ± √Δ)/(2a). If Δ < 0, the roots are complex: real part = -b/(2a), imaginary part = ±√|Δ|/(2a).
📝 Worked Example: x² - 5x + 6 = 0
Step 1: Δ = 25 - 24 = 1 > 0 → two real roots
Step 2: x = (5 ± 1) / 2 = 3 or 2
Result: x₁ = 3, x₂ = 2
⚠️ Common Mistakes to Avoid
- a = 0: Then it's linear, not quadratic. Use linear methods.
- Wrong sign in formula: x = (-b ± √Δ)/(2a). The -b is critical.
- Forgetting 2a: The denominator is 2a, not 2.
🎯 Expert Tips
💡 Vieta Verification
x₁ + x₂ = -b/a and x₁ × x₂ = c/a. Check your roots.
💡 Factoring Shortcut
If roots are integers, try factoring first (e.g., x²-5x+6 = (x-2)(x-3)).
❓ FAQ
What if a = 0?
Then the equation is linear (bx + c = 0), not quadratic. Use linear methods.
Can I get exact roots?
For integer coefficients and perfect-square discriminant, yes. Otherwise you get decimals or radicals.
What is the vertex?
The vertex is at x = -b/(2a), y = f(-b/(2a)) = c - b²/(4a).
Why complex roots?
When Δ < 0, √Δ is imaginary. The roots are conjugates: p ± qi.
How do I verify?
Substitute each root into ax² + bx + c; the result should be 0.
⚠️ Disclaimer: This calculator provides numerical solutions. For exact symbolic form with radicals, use a computer algebra system.
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