Given √2 ≈ 1.4142, compute the value of 7 / (3 + √2). Provide the result to four decimal places.

Aptitude Square Root and Cube Root Difficulty: Easy
Choose an option
  • A
    1.5858
  • B
    4.4142
  • C
    3.4852
  • D
    3.5858

Answer

Correct Answer: 1.5858

Explanation

Introduction / Context: This is a straightforward evaluation of a rational expression involving a radical in the denominator. Rationalization provides insight; approximation provides a quick decimal answer.

Given Data / Assumptions:

  • √2 ≈ 1.4142.
  • Expression: 7 / (3 + √2).
  • Round to four decimal places.

Concept / Approach: Either directly substitute √2 and compute, or rationalize by multiplying numerator and denominator by (3 − √2) to check the magnitude. Both lead to the same decimal result.

Step-by-Step Solution: Direct evaluation: denominator = 3 + 1.4142 = 4.4142. Value = 7 / 4.4142 ≈ 1.5858.

Verification / Alternative check: Rationalize: 7 / (3 + √2) = 7(3 − √2) / (9 − 2) = 7(3 − √2) / 7 = 3 − √2 ≈ 3 − 1.4142 = 1.5858, confirming the result.

Why Other Options Are Wrong: 4.4142 is the denominator, not the value. 3.4852 and 3.5858 are unrelated approximations and not equal to 3 − √2.

Common Pitfalls: Confusing the denominator with the final result, or forgetting to round consistently.

Final Answer: 1.5858

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