Difficulty: Easy
Correct Answer: 5
Explanation:
Introduction / Context:This problem directly uses a well-known algebraic identity. When x + y + z ≠ 0, the expression (x^3 + y^3 + z^3 - 3xyz) / (x^2 + y^2 + z^2 - xy - yz - zx) simplifies elegantly to x + y + z.
Given Data / Assumptions:
Concept / Approach:Use the identity: (x^3 + y^3 + z^3 - 3xyz) / (x^2 + y^2 + z^2 - xy - yz - zx) = x + y + z, provided x + y + z ≠ 0. Here, the numbers are chosen so their sum is exact and simple.
Step-by-Step Solution:
Compute sum: x + y + z = 2.247 + 1.730 + 1.023 = 5.000By identity, the entire fraction simplifies to x + y + z = 5Verification / Alternative check:
You can numerically evaluate numerator and denominator separately, but the identity guarantees the result as long as x + y + z ≠ 0.Why Other Options Are Wrong:
Common Pitfalls:
Final Answer:
5
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