Difficulty: Easy
Correct Answer: 0.318
Explanation:
Introduction / Context:
This numerical approximation problem practices handling radicals and reciprocals. Rationalization gives an exact form, while given approximations yield the decimal result.
Given Data / Assumptions:
Concept / Approach:
Using the conjugate: 1 / (√3 + √2) = (√3 − √2) / [(√3 + √2)(√3 − √2)] = (√3 − √2) / (3 − 2) = √3 − √2. Then substitute the approximations.
Step-by-Step Solution:
1 / (√3 + √2) = √3 − √2. ≈ 1.732 − 1.414 = 0.318. To three decimals, the value is 0.318.
Verification / Alternative check:
Direct division: 1 / (1.732 + 1.414) ≈ 1 / 3.146 ≈ 0.3179, which rounds to 0.318 and matches the conjugate method.
Why Other Options Are Wrong:
0.064 and 0.308 deviate from the rationalized exact form √3 − √2. 2.146 is vastly too large for a reciprocal of a number greater than 3.
Common Pitfalls:
Forgetting to rationalize or incorrectly subtracting decimal approximations may produce small but significant errors. Always check with both methods if unsure.
Final Answer:
0.318
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