Math Problem Statement

how do we solve cubic equation in genersl ?

Solution

Solving cubic equations, or equations of the form ax3+bx2+cx+d=0ax^3 + bx^2 + cx + d = 0, can be approached in several ways. Here’s an overview of the most common methods:

1. Factorization (if possible)

The easiest method for solving cubic equations is to factorize them. If you can find one or more factors, you can break the cubic equation down into simpler quadratic or linear factors.

Steps:

  • Find rational roots: Use the Rational Root Theorem to test possible rational roots. The theorem suggests that any rational root is a factor of the constant term dd divided by a factor of the leading coefficient aa.
  • Synthetic division or polynomial division: Once a root is found, use synthetic or polynomial division to reduce the cubic to a quadratic equation.
  • Solve the quadratic: Solve the quadratic equation using the quadratic formula, factoring, or completing the square.

Example: x36x2+11x6=0x^3 - 6x^2 + 11x - 6 = 0 Test possible roots x=1x = 1, x=2x = 2, and x=3x = 3. If x=1x = 1 is a root, divide the cubic by (x1)(x - 1), then solve the resulting quadratic.

2. Graphical Methods

If finding

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Math Problem Analysis

Mathematical Concepts

Algebra
Cubic Equations
Factorization
Polynomial Division

Formulas

Cubic equation: ax^3 + bx^2 + cx + d = 0
Quadratic equation: ax^2 + bx + c = 0

Theorems

Rational Root Theorem

Suitable Grade Level

Grades 10-12