111- The limit of $\dfrac{\sqrt{\cos 3x} - \sqrt{\cos x}}{x^2}$ as $x \to 0$ is which of the following? (1) $-2$ (2) $-\dfrac{1}{2}$ (3) $\dfrac{1}{2}$ (4) $2$
\textbf{111-} The limit of $\dfrac{\sqrt{\cos 3x} - \sqrt{\cos x}}{x^2}$ as $x \to 0$ is which of the following?
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(1) $-2$ \hfill (2) $-\dfrac{1}{2}$ \hfill (3) $\dfrac{1}{2}$ \hfill (4) $2$
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