三次方程式計算機

共有リンク

はじめに

Cubic Equation Calculator — Solve cubic equations of the form ax^3+bx^2+cx+d=0. Enter a, b, c, d to get an instant, accurate result.

計算式

Solves ax³+bx²+cx+d=0 using Cardano's method: the equation is depressed to t³+pt+q=0, and the discriminant (q²/4 + p³/27) determines whether there is one real root or three.

ステップごとの説明

Enter the a.
Enter the b.
Enter the c.
Enter the d.
Click Calculate to see your result instantly.

実例

Example: With a = 1, b = -6, c = 11, d = -6, the Cubic Equation Calculator gives Roots: 3, 1, 2.

よくある質問

How many roots does a cubic have?

Always three (counting multiplicity and complex roots), but this calculator returns one or three real roots depending on the discriminant.

What if a = 0?

That's not a true cubic equation — the calculator requires a nonzero leading coefficient.

What inputs does the Cubic Equation Calculator need?

You'll need to provide: a, b, c, d. All fields use sensible defaults, so you can see a working example immediately and then adjust the values to match your own numbers.

How accurate is the Cubic Equation Calculator?

The Cubic Equation Calculator applies the formula exactly as calculated — Solves ax³+bx²+cx+d=0 using Cardano's method: the equation is depressed to t³+pt+q=0, and the discriminant (q²/4 + p³/27) determines whether there is one real root or three. — so results are precise for the inputs you provide. Accuracy depends on entering correct, realistic input values.

Is the Cubic Equation Calculator free to use?

Yes, the Cubic Equation Calculator is completely free, requires no signup, and runs instantly in your browser.