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Discuss the continuity of the function f(x) at the point x = 1/2, where f ( x ) = ⎧ ⎪ ⎪ ⎨ ⎪ ⎪ ⎩ x , 0 ≤ x < 1 2 1 2 , x = 1 2 1 − x , 1 2 < x ≤ 1 - Mathematics

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Question

Discuss the continuity of the function f(x) at the point x = 1/2, where \[f\left( x \right) = \begin{cases}x, 0 \leq x < \frac{1}{2} \\ \frac{1}{2}, x = \frac{1}{2} \\ 1 - x, \frac{1}{2} < x \leq 1\end{cases}\] 

Sum
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Solution

Given: 

\[f\left( x \right) = \begin{cases}x, 0 \leq x < \frac{1}{2} \\ \frac{1}{2}, x = \frac{1}{2} \\ 1 - x, \frac{1}{2} < x \leq 1\end{cases}\]

We observe

(LHL at x =\[\frac{1}{2}\]

\[\lim_{x \to \frac{1}{2}^-} f\left( x \right) = \lim_{h \to 0} f\left( \frac{1}{2} - h \right)\]

\[\lim_{h \to 0} \left( \frac{1}{2} - h \right) = \frac{1}{2}\]

(RHL at x = \[\frac{1}{2}\]

\[\lim_{x \to \frac{1}{2}^+} f\left( x \right) = \lim_{h \to 0} f\left( \frac{1}{2} + h \right)\]

\[\lim_{h \to 0} \left( 1 - \left( \frac{1}{2} + h \right) \right) = \frac{1}{2}\]

Also, ​

\[f\left( \frac{1}{2} \right) = \frac{1}{2}\]

\[\therefore \lim_{x \to \frac{1}{2}^-} f\left( x \right) = \lim_{x \to \frac{1}{2}^+} f\left( x \right) = f\left( \frac{1}{2} \right)\]

Hence, 

\[f\left( x \right)\] is continuous at 

\[x = \frac{1}{2}\] .

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Chapter 9: Continuity - Exercise 9.1 [Page 18]

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RD Sharma Mathematics [English] Class 12
Chapter 9 Continuity
Exercise 9.1 | Q 16 | Page 18

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