Solving Cubic Equations: A Comprehensive Guide

Introduction

Cubic equations have intrigued mathematicians for centuries due to their complexity and the variety of solutions they offer. This guide will explore how to solve cubic equations, focusing on a specific example and detailing the steps involved in finding solutions using algebraic methods and polynomial factoring. The article is designed to meet Google's standards for high-quality content, engaging and informative for both students and professionals in the field.

Understanding Cubic Equations

A cubic equation is an algebraic equation of the form

(a x^3 b x^2 c x d 0)

where (a) is non-zero. These equations can have up to three roots, which may be real or complex numbers.

Solving the Specific Cubic Equation

Example Equation: (tau^2 - tau^3 12^2 - 12^3)

Let's solve the cubic equation given by:

(tau^2 - tau^3 12^2 - 12^3)

Step 1: Simplifying the Equation

First, let's simplify the right-hand side:

(tau^2 - tau^3 144 - 1728 -1584)

Step 2: Rearranging the Equation

Rearrange the equation to standard polynomial form:

(tau^3 - tau^2 - 1584 0)

Step 3: Finding an Obvious Root

The equation can be factored by trial and error or inspection. We notice that:

((-12)) is a root because substituting (tau 12) into the equation gives:

(12^3 - 12^2 - 1584 1728 - 144 - 1584 0)

Step 4: Factoring the Polynomial

By factoring out ((tau - 12)), we can simplify the polynomial:

Note that:

(tau^3 - tau^2 - 1584 (tau - 12)(tau^2 11tau 132))

Step 5: Solving the Quadratic Equation

The quadratic equation

(tau^2 11tau 132 0)

can be solved using the quadratic formula:

(tau frac{-b pm sqrt{b^2 - 4ac}}{2a})

Here, (a 1), (b 11), and (c 132). Plugging in these values, we get:

(tau frac{-11 pm sqrt{(11)^2 - 4 cdot 1 cdot 132}}{2 cdot 1})

(tau frac{-11 pm sqrt{121 - 528}}{2})

(tau frac{-11 pm sqrt{-407}}{2})

(tau frac{-11 pm isqrt{407}}{2})

Thus, the solutions to the quadratic equation are:

(tau frac{-11 isqrt{407}}{2}) and (tau frac{-11 - isqrt{407}}{2})

Conclusion

In summary, the cubic equation (tau^2 - tau^3 12^2 - 12^3) simplifies to (tau^3 - tau^2 - 1584 0). The solutions are:

1. (tau 12) (a real root)

2. (tau frac{-11 isqrt{407}}{2})

3. (tau frac{-11 - isqrt{407}}{2})

These solutions showcase the diverse nature of cubic equations and the methods used to solve them, providing a valuable resource for anyone studying advanced mathematics.

[Note: The approximation for (sqrt{407}) is given for educational purposes and is not strictly necessary for solving the problem as stated.]