Difficulty: Easy
Correct Answer: 3
Explanation:
Introduction / Context:
When x satisfies a quadratic, expressions like x + 1/x can be simplified by using the quadratic to eliminate x^2. This avoids explicitly solving for x and keeps the algebra light and clean.
Given Data / Assumptions:
Concept / Approach:
Compute x + 1/x = (x^2 + 1)/x. Replace x^2 using the given quadratic: x^2 = 3x − 1. This method is standard for symmetric expressions in x and 1/x.
Step-by-Step Solution:
x + 1/x = (x^2 + 1)/xGiven x^2 = 3x − 1Hence (x^2 + 1)/x = (3x − 1 + 1)/x = 3x/x = 3
Verification / Alternative check:
Alternatively, divide the original equation by x: x − 3 + 1/x = 0 ⇒ x + 1/x = 3, same result.
Why Other Options Are Wrong:
0, 2, 1, −1 do not match the identity derived directly from the quadratic.
Common Pitfalls:
Forgetting to ensure x ≠ 0 (it is not a root here), or mishandling algebra when substituting x^2.
Final Answer:
3
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