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Determine the Value of the Constant 'K' So that Function F ( X ) = { K X | X | , If X < 0 3 , If X ≥ 0 is Continuous at X = 0 .

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Question

Determine the value of the constant 'k' so that function 

\[\left( x \right) = \begin{cases}\frac{kx}{\left| x \right|}, &\text{ if }  x < 0 \\ 3 , & \text{ if } x \geq 0\end{cases}\]  is continuous at x  = 0  . 
Sum
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Solution

\[\text{ Given } , f(x) = \begin{cases}\frac{kx}{\left| x \right|} & , \text{ if } x < 0 \\ 3 & , \text{ if } x \geqslant 0\end{cases}\]

Since the function is continuous at x = 0, therefore,

\[\lim_{x \to 0^-} f(x) = \lim_{x \to 0^+} f(x) = f(0)\]
\[ \Rightarrow \lim_{x \to 0} \frac{- kx}{x} = \lim_{x \to 0} 3 = 3\]
\[ \Rightarrow - k = 3\]
\[ \Rightarrow k = - 3\]

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Chapter 8: Continuity - Exercise 9.3 [Page 42]

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R.D. Sharma Mathematics Volume 1 and 2 [English] Class 12
Chapter 8 Continuity
Exercise 9.3 | Q 11 | Page 42

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