if √x - 1/√x = 3√2, then x2 + 1/x2 is equal to:
Show answer & explanation
Correct answer: A
Explanation
Correct Answer is option 1 i.e. 398
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Concept |
Application |
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(x – 1/x)2 = x2 + 1/x2 – 2 |
Given √x– 1/√x = 3√2 Squaring both sides: ⇒ x + 1/x – 2 = 18 ⇒ x + 1/x = 20 Squaring again: ⇒ x2 + 1/x2 + 2 = 400 ⇒ x2 + 1/x2 = 398 |