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Difficulty: 2/102023 NMTC 2023 (QI-15)

If + 1/x = 2, then the value of x^2 + 1/x^2 is:

Options:

  • A.

    1/4

  • B.

    1

  • C.

    3

  • 2

Guide / Hint

Hint 1: Square both sides of the equation .

Hint 2: Use the identity , noting that the cross-product is 2.

Hint 3: Subtract 2 from the squared result to find the answer.

Solution

Step 1 (Square both sides): We are given . Squaring both sides of the equation:

Step 2 (Simplify the Middle Term): Since :

Step 3 (Isolate the Target Term): Subtract 2 from both sides:

Step 4 (Conclusion): The value is , which is option index 3 in ['1/4', '1', '3', '2'].

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    2023 NMTC 2023 QI-15 - Olympiad Math Olympiad Question | Leminno