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Discuss the Continuity of the Following Functions at the Indicated Point(S): (I) F ( X ) = { | X | Cos ( 1 X ) , X ≠ 0 0 , X = 0 a T X = 0 - Mathematics

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Question

Discuss the continuity of the following functions at the indicated point(s): 

(i) \[f\left( x \right) = \begin{cases}\left| x \right| \cos\left( \frac{1}{x} \right), & x \neq 0 \\ 0 , & x = 0\end{cases}at x = 0\]

 

Solution

(i) Given: 

\[f\left( x \right) = \binom{\left| x \right| \cos\left( \frac{1}{x} \right), x \neq 0}{0, x = 0}\]

We observe

\[\lim_{x \to 0} f\left( x \right) = \lim_{x \to 0} \left| x \right| \cos\left( \frac{1}{x} \right)\] 

\[ \Rightarrow \lim_{x \to 0} f\left( x \right) = \lim_{x \to 0} \left| x \right| \lim_{x \to 0} \cos\left( \frac{1}{x} \right)\] 

\[ \Rightarrow \lim_{x \to 0} f\left( x \right) = 0 \times \lim_{x \to 0} \cos\left( \frac{1}{x} \right) = 0\]

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

Hence, f(x) is continuous at x = 0.

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Chapter 9: Continuity - Exercise 9.1 [Page 17]

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RD Sharma Mathematics [English] Class 12
Chapter 9 Continuity
Exercise 9.1 | Q 10.1 | Page 17

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