Difficulty: Easy
Correct Answer: 0.14
Explanation:
Introduction / Context:
This problem is a classic application of polynomial identities with decimals. Recognizing the form (a^3 − b^3) / (a^2 + ab + b^2) immediately simplifies computation and avoids long decimal multiplications.
Given Data / Assumptions:
Concept / Approach:
Use the identity a^3 − b^3 = (a − b)(a^2 + ab + b^2). Dividing by (a^2 + ab + b^2) cancels that factor, leaving simply a − b. This identity works for any real numbers a, b, including decimals.
Step-by-Step Solution:
Start with (a^3 − b^3) / (a^2 + ab + b^2).Apply the factorization: a^3 − b^3 = (a − b)(a^2 + ab + b^2).Cancel the common factor (a^2 + ab + b^2): result = a − b.Compute a − b = 0.47 − 0.33 = 0.14.
Verification / Alternative check:
Approximate multiplication confirms the same outcome but is longer. The identity ensures exactness with far less effort.
Why Other Options Are Wrong:
Common Pitfalls:
Multiplying out cubes and squares directly and committing rounding errors; forgetting the exact identity that dramatically reduces work.
Final Answer:
0.14
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