Math Problem Statement

Determine all possible values of the expression A^3 + B^3 + C^3 - 3ABC, where A, B, and C are nonnegative integers.

Solution

To determine all possible values of the expression A3+B3+C33ABCA^3 + B^3 + C^3 - 3ABC, where AA, BB, and CC are nonnegative integers, we can utilize a useful algebraic identity.

The expression A3+B3+C33ABCA^3 + B^3 + C^3 - 3ABC can be factored using the identity:

A3+B3+C33ABC=(A+B+C)(A2+B2+C2ABBCCA)A^3 + B^3 + C^3 - 3ABC = (A+B+C)(A^2 + B^2 + C^2 - AB - BC - CA)

Analysis of the Identity

  1. If A+B+C=0A + B + C = 0:

    • Since AA, BB, and CC are nonnegative integers, the only way this can happen is if A=B=C=0A = B = C = 0.
    • Substituting A=B=C=0A = B = C = 0 into the expression, we get: 03+03+033000=00^3 + 0^3 + 0^3 - 3 \cdot 0 \cdot 0 \cdot 0 = 0
    • Hence, 0 is a possible value.
  2. If A+B+C>0A + B + C > 0:

    • In this case, (A+B+C)(A+B+C) is a positive integer.
    • The term (A2+B2+C2ABBCCA)(A^2 + B^2 + C^2 - AB - BC - CA) represents a nonnegative integer because it is equivalent to: 12((AB)2+(BC)2+(CA)2)\frac{1}{2} \left( (A-B)^2 + (B-C)^2 + (C-A)^2 \right)
    • Thus, the entire product (A+B+C)(A2+B2+C2ABBCCA)(A+B+C)(A^2 + B^2 + C^2 - AB - BC - CA) is a nonnegative integer.

Observations

  • The identity shows that for any nonnegative integers AA, BB, and CC, the expression A3+B3+C33ABCA^3 + B^3 + C^3 - 3ABC simplifies to a nonnegative integer.
  • As demonstrated, A3+B3+C33ABCA^3 + B^3 + C^3 - 3ABC can be zero if A=B=C=0A = B = C = 0.
  • For other nonnegative integer values of AA, BB, and CC, the expression will be some nonnegative integer based on the specific values of AA, BB, and CC.

Conclusion

The possible values of the expression A3+B3+C33ABCA^3 + B^3 + C^3 - 3ABC are all nonnegative integers, including zero.

Would you like further details or have any specific questions?

Here are 5 more questions you might find interesting:

  1. What are the roots of the polynomial x36x2+11x6x^3 - 6x^2 + 11x - 6?
  2. How do you solve a system of linear equations using matrix methods?
  3. Can you explain the method of completing the square for quadratic equations?
  4. What is the significance of the determinant of a matrix?
  5. How do you find the derivative of a composite function using the chain rule?

Tip: When tackling algebraic identities, try to recognize common factorization patterns which can simplify solving the equations.

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Math Problem Analysis

Mathematical Concepts

Algebra
Factorization
Number Theory

Formulas

Algebraic identity for A^3 + B^3 + C^3 - 3ABC

Theorems

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Suitable Grade Level

Grades 9-12