Math Problem Statement

(a+b+c) (ab+bc+ca)= abc, then what is (a+b+c)^3

Solution

We start with the given equation:

(a+b+c)(ab+bc+ca)=abc(a + b + c)(ab + bc + ca) = abc

Step 1: Expand (a+b+c)3(a + b + c)^3

The expression (a+b+c)3(a + b + c)^3 can be expanded as:

(a+b+c)3=a3+b3+c3+3(a2b+b2a+b2c+c2b+c2a+a2c)+6abc(a + b + c)^3 = a^3 + b^3 + c^3 + 3(a^2b + b^2a + b^2c + c^2b + c^2a + a^2c) + 6abc

Alternatively, it can be written using the identity:

(a+b+c)3=a3+b3+c3+3(a+b+c)(ab+bc+ca)3abc(a + b + c)^3 = a^3 + b^3 + c^3 + 3(a + b + c)(ab + bc + ca) - 3abc

Step 2: Use the given equation

From the problem, we know:

(a+b+c)(ab+bc+ca)=abc(a + b + c)(ab + bc + ca) = abc

Substituting this into the expansion:

(a+b+c)3=a3+b3+c3+3abc3abc(a + b + c)^3 = a^3 + b^3 + c^3 + 3 \cdot abc - 3 \cdot abc

This simplifies to:

(a+b+c)3=a3+b3+c3(a + b + c)^3 = a^3 + b^3 + c^3

Thus, the result for (a+b+c)3(a + b + c)^3 depends only on the individual cubes a3a^3, b3b^3, and c3c^3, with no additional terms.

Would you like a further breakdown or examples of how this might apply? Here are five questions to consider:

  1. What specific values for a,b,ca, b, c satisfy the given condition?
  2. Can we derive a similar equation if (a+b+c)(a + b + c) and (ab+bc+ca)(ab + bc + ca) follow different relationships?
  3. What happens if a,b,ca, b, c are negative or complex numbers?
  4. How does this result relate to symmetric polynomial identities?
  5. What are the implications for roots of polynomials with a,b,ca, b, c as roots?

Tip: Symmetric identities often simplify polynomial expressions; try to group terms by symmetry for clarity.

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Math Problem Analysis

Mathematical Concepts

Algebra
Symmetric Polynomials
Expanding Polynomials
Cube Expansion

Formulas

(a + b + c)^3 = a^3 + b^3 + c^3 + 3(a^2b + b^2a + b^2c + c^2b + c^2a + a^2c) + 6abc
(a + b + c)^3 = a^3 + b^3 + c^3 + 3(a + b + c)(ab + bc + ca) - 3abc

Theorems

Binomial Expansion
Symmetric Polynomial Identities

Suitable Grade Level

Grades 11-12