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Question
Define continuity of a function at a point.
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Solution
Continuity at a point:
\[ \Leftrightarrow \lim_{x \to a} f\left( x \right) = f\left( a \right) \Leftrightarrow \lim_{x \to a^-} f\left( x \right) = \lim_{x \to a^+} f\left( x \right) = f\left( a \right)\]
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