The \[\mathop {\lim }\limits_{{\text{x}} \to 0} \frac{{\sin \left[ {\frac{2}{3}{\text{x}}} \right]}}{{\text{x}}}\] is A. \[\frac{2}{3}\] B. 1 C. \[\frac{3}{2}\] D. \[\infty \]

”[rac{2}{3}\
” option2=”1″ option3=”\[\frac{3}{2}\]” option4=”\[\infty \]” correct=”option3″]

The correct answer is $\boxed{\frac{2}{3}}$.

The limit $\mathop {\lim }\limits_{{\text{x}} \to 0} \frac{{\sin \left[ {\frac{2}{3}{\text{x}}} \right]}}{{\text{x}}}$ can be evaluated using L’Hôpital’s rule. L’Hôpital’s rule states that if $\mathop {\lim }\limits_{{\text{x}} \to 0} \frac{{f\left( {\text{x}} \right)}}{{g\left( {\text{x}} \right)}}$ exists and $\mathop {\lim }\limits_{{\text{x}} \to 0} \frac{{f’\left( {\text{x}} \right)}}{{g’\left( {\text{x}} \right)}}$ also exists, then $\mathop {\lim }\limits_{{\text{x}} \to 0} \frac{{f\left( {\text{x}} \right)}}{{g\left( {\text{x}} \right)}} = \mathop {\lim }\limits_{{\text{x}} \to 0} \frac{{f’\left( {\text{x}} \right)}}{{g’\left( {\text{x}} \right)}}$.

In this case, we have $f\left( {\text{x}} \right) = \sin \left[ {\frac{2}{3}{\text{x}}} \right]$ and $g\left( {\text{x}} \right) = {\text{x}}$. Therefore, we have

$$\begin{align}
\mathop {\lim }\limits_{{\text{x}} \to 0} \frac{{\sin \left[ {\frac{2}{3}{\text{x}}} \right]}}{{\text{x}}} &= \mathop {\lim }\limits_{{\text{x}} \to 0} \frac{{f’\left( {\text{x}} \right)}}{{g’\left( {\text{x}} \right)}} \\
&= \mathop {\lim }\limits_{{\text{x}} \to 0} \frac{{2\cos \left[ {\frac{2}{3}{\text{x}}} \right] \cdot \frac{2}{3}}}{{1}} \\
&= \frac{2}{3}.
\end{align
}$$

Therefore, the limit $\mathop {\lim }\limits_{{\text{x}} \to 0} \frac{{\sin \left[ {\frac{2}{3}{\text{x}}} \right]}}{{\text{x}}}$ is $\boxed{\frac{2}{3}}$.

The other options are incorrect because they do not represent the correct value of the limit.

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