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In the Following, Determine the Value of Constant Involved in Definition So that Given Function is Continuou: \[F\Left( X \Right) = \Begin{Cases}\Frac{\Sin 2x}{ and \Text{ If } X \Neq 0 \\ 3k

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Question

In the following, determine the value of constant involved in the definition so that the given function is continuou:  \[f\left( x \right) = \begin{cases}\frac{\sin 2x}{5x}, & \text{ if }  x \neq 0 \\ 3k , & \text{ if  } x = 0\end{cases}\] 

Sum
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Solution

Given:

\[f\left( x \right) = \begin{cases}\frac{\sin 2x}{5x}, & \text{ if }  x \neq 0 \\ 3k , & \text{ if  } x = 0\end{cases}\] 
If  
\[f\left( x \right)\]  is continuous at x = 0, then 
\[\lim_{x \to 0} f\left( x \right) = f\left( 0 \right)\]
\[\Rightarrow \lim_{x \to 0} \frac{\sin 2x}{5x} = f\left( 0 \right)\]
\[ \Rightarrow \lim_{x \to 0} \frac{2\sin 2x}{2 \times 5x} = f\left( 0 \right)\]
\[ \Rightarrow \frac{2}{5} \lim_{x \to 0} \frac{\sin 2x}{2x} = f\left( 0 \right)\]
\[ \Rightarrow \frac{2}{5} = 3k\]
\[ \Rightarrow k = \frac{2}{15}\]
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Chapter 8: Continuity - Exercise 9.2 [Page 35]

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R.D. Sharma Mathematics Volume 1 and 2 [English] Class 12
Chapter 8 Continuity
Exercise 9.2 | Q 4.1 | Page 35

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