\(2x + \frac{2}{x} = 3\) হলে, \({x^2} + \frac{1}{{{x^2}}}\) এর মান কত ? 

A  1/2 

B  1/4 

C  2/3 

D  6/10 

E  

Solution

Correct Answer: Option B

Solution: 

   \(2x + \frac{2}{x} = 3\)      => \(2(x + \frac{1}{x}) = 3\)     => \({(x + \frac{1}{x})^{2\;}} = {(\frac{3}{2})^{2\;}}\)  

  => \({x^{2\;}} + \frac{1}{{{x^{2\;}}}} + 2 \times x \times \frac{1}{x} = \frac{9}{4}\)     => \({x^{2\;}} + \frac{1}{{{x^{2\;}}}} = \frac{9}{4} - 2\) 

 => \({x^{2\;}} + \frac{1}{{{x^{2\;}}}} = \frac{{9 - 8}}{4} = \frac{1}{4}\)                   \({x^{2\;}} + \frac{1}{{{x^{2\;}}}} = \frac{1}{4}\) 

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