Exams › SSC CGL (Prelims) › General

If x + 1/x = 2, evaluate the expression (x^8 + 1/x^8) - 2(x^6 + 1/x^6) + 5(x^2 + 1/x^2).

1. 4
2. 8
3. 10
4. 6

Correct answer: 8

Solution

x + 1/x = 2 implies x = 1. Then every term x^n + 1/x^n equals 2, so the expression is 2 - 2(2) + 5(2) = 2 - 4 + 10 = 8.

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