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Find Lim X → 3 F ( X ) Where F ( X ) = { 4 , I F X > 3 X + 1 , I F X < 3 - Mathematics

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Question

Find \[\lim_{x \to 3} f\left( x \right)\] where \[f\left( x \right) = \begin{cases}4, & if x > 3 \\ x + 1, & if x < 3\end{cases}\] 

Solution

We have, 

\[f\left( x \right) = \begin{cases}4, & if x > 3 \\ x + 1, & if x < 3\end{cases}\] 

LHL of f(x) at x = 3 

= \[\lim_{x \to 3^-} f\left( x \right) = \lim_{h \to 0} f\left( 3 - h \right) = \lim_{h \to 0} \left( 3 - h + 1 \right) = 4\] 

RHL of f(x) at x = 3 

= \[\lim_{x \to 3^+} f\left( x \right) = \lim_{h \to 0} f\left( 3 + h \right) = \lim_{h \to 0} 4 = 4\] 

Clearly,

\[\lim_{x \to 3^-} f\left( x \right) = \lim_{x \to 3^+} f\left( x \right) = 4\] 
\[\therefore \lim_{x \to 3} f\left( x \right) = 4\] 
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Chapter 29: Limits - Exercise 29.1 [Page 11]

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RD Sharma Mathematics [English] Class 11
Chapter 29 Limits
Exercise 29.1 | Q 7 | Page 11

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