Pemecah persamaan kubik khusus dengan akar nyata dan kompleks, langkah-langkah metode Cardano, grafik kubik, dan contoh kerja.
Kalkulator Diskriminan Kubik
Masukkan koefisien polinomial Anda di atas dan klik "Hitung Diskriminan" untuk melihat hasilnya.The discriminant of a cubic equation is a single numerical value, denoted Δ, that instantly reveals the nature of all three roots without solving the equation. For the general cubic ax³ + bx² + cx + d = 0, the discriminant formula is Δ = 18abcd − 4b³d + b²c² − 4ac³ − 27a²d². This expression encodes the geometric relationship between the curve and the x-axis.
When Δ > 0, the cubic has three distinct real roots — the curve crosses the x-axis at three separate points. When Δ = 0, at least two roots coincide, meaning the curve is tangent to the x-axis at one or more points. When Δ < 0, there is exactly one real root and a pair of complex conjugate roots — the curve crosses the x-axis only once.
The discriminant serves as a classification gateway in algebra and engineering. Before investing effort into solving, you can determine whether to expect real or complex solutions. This is especially valuable in structural analysis, control systems, and optimization problems where the nature of roots determines system stability.
Determine whether a control system has oscillatory (complex) or overdamped (real) behavior based on its characteristic cubic equation.
Predict phase transitions modeled by cubic free-energy equations — the discriminant reveals whether single or multiple phases coexist.
Assess whether profit models have multiple break-even points or a single crossing, guiding pricing strategy decisions.
The discriminant formula is long. Omitting the last term is common and leads to incorrect root-type classification.
The quadratic discriminant b²−4ac is simpler. Don't accidentally use it for cubics — they require the full 5-term expression.
For quadratics, Δ>0 means 2 real roots. For cubics, Δ>0 means 3 real roots. Keep the conventions straight.
| Formula | Δ = 18abcd − 4b³d + b²c² − 4ac³ − 27a²d² |
| Δ > 0 | Three distinct real roots |
| Δ = 0 | At least two equal real roots |
| Δ < 0 | One real root, two complex conjugate roots |
| Input | Coefficients a, b, c, d |
| Output | Discriminant value + root classification |
Tidak, ini hanya memberi tahu Anda *jenis* akar apa yang ada. Anda memerlukan pemecah khusus untuk menemukan nilai yang tepat.
Cukup masukkan 0 untuk<span class="font-mono text-primary-700 bg-primary-50 px-1 rounded">B</span>koefisien. Kalkulator menangani istilah yang hilang dengan mudah.
Ya, diskriminan nol berarti kurva hanya menyentuh sumbu x, sehingga menghasilkan akar yang berulang (berganda).
Diskriminan positif (Δ > 0) berarti persamaan kubik mempunyai tiga akar real berbeda.
Diskriminan negatif (Δ < 0) berarti persamaan kubik mempunyai satu akar real dan dua akar konjugasi kompleks.
