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The Function F ( X ) = { Sin 3 X X , X ≠ 0 K 2 , X = 0 is Continuous at X = 0, Then K = (A) 3 (B) 6 (C) 9 (D) 12 - Mathematics

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Question

The function 

\[f\left( x \right) = \begin{cases}\frac{\sin 3x}{x}, & x \neq 0 \\ \frac{k}{2} , & x = 0\end{cases}\]  is continuous at x = 0, then k =

Options

  • 3

  • 6

  • 9

  • 12

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Solution

\[f\left( x \right) = \binom{\frac{\sin 3x}{x}}{\frac{k}{2}, x = 0}, x \neq 0\]

If   \[f\left( x \right)\]  is continuous at  \[x = 0\] , then

\[\lim_{x \to 0} f\left( x \right) = f\left( 0 \right)\]

\[\Rightarrow \lim_{x \to 0} \frac{\sin 3x}{x} = f\left( 0 \right)\]
\[ \Rightarrow 3 \lim_{x \to 0} \frac{\sin 3x}{3x} = \frac{k}{2}\]
\[ \Rightarrow 3 \times 1 = \frac{k}{2}\]
\[ \Rightarrow \frac{k}{2} = 3\]
\[ \Rightarrow k = 6\]

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Chapter 9: Continuity - Exercise 9.4 [Page 45]

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RD Sharma Mathematics [English] Class 12
Chapter 9 Continuity
Exercise 9.4 | Q 25 | Page 45

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