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∞ ∫ 0 E − X D X - Mathematics

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Question

\[\int\limits_0^\infty e^{- x} dx\]
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Solution

\[Let\ I = \int_0^\infty e^{- x} d\ x\ . Then, \]
\[I = \left[ - e^{- x} \right]_0^\infty \]
\[ \Rightarrow I = - e^{- \infty} + e^0 \]
\[ \Rightarrow I = 0 + 1\]
\[ \Rightarrow I = 1\]

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Definite Integrals
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Chapter 20: Definite Integrals - Exercise 20.1 [Page 16]

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RD Sharma Mathematics [English] Class 12
Chapter 20 Definite Integrals
Exercise 20.1 | Q 8 | Page 16

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