A) \[\sqrt{32}\]
B) \[\sqrt{49}\]
C) \[\sqrt{140}\]
D) None of these
Correct Answer: A
Solution :
\[6=a+\frac{1}{a}={{\left( \sqrt{a} \right)}^{2}}-2+{{\left( \frac{1}{\sqrt{a}} \right)}^{2}}+2={{\left( \sqrt{a}-\frac{1}{\sqrt{a}} \right)}^{2}}+2\]\[\therefore \]\[{{\left( \sqrt{a}-\frac{1}{\sqrt{a}} \right)}^{2}}=4\] Now, \[\left( a-\frac{1}{a} \right)={{\left( \sqrt{a} \right)}^{2}}+2+{{\left( \frac{1}{\sqrt{a}} \right)}^{2}}\]
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