Could someone please explain how to solve this problem. Cheers troops.
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$\displaystyle \begin{gathered} \left( {a - b} \right)^2 \geqslant 0 \Rightarrow \quad a^2 + b^2 \geqslant 2ab \hfill \\ \text{let }a = \sqrt x \,\& \,b = \frac{1} {{\sqrt x }} \hfill \\ \end{gathered} $
And since you're in calculus, you can also differentiate the function $\displaystyle f(x)=x+\frac 1x$ and see its variations
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