SSC CPO 15th-March-2019-Shift-1

Question 105

If $$x+\frac{1}{x}=2\sqrt{3}$$, then $$x^2+\frac{1}{x^2}$$ is equal to:

Solution

$$(x+1/x)^2=x^2+1/x^2+2×x×(1/x).$$

$$=x^2+1/x^2+2.$$

So,$$x^2+1/x^2+2=(2√3)^2=12.$$

or,$$x^2+1/x^2=10.$$

C is correct choice.

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