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If X = E X / Y , Prove that D Y D X = X − Y X Log X ? - Mathematics

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Question

\[\text{ If } x = e^{x/y} , \text{ prove that } \frac{dy}{dx} = \frac{x - y}{x\log x}\] ?
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Solution

\[x = e^\frac{x} {y} \]
\[\text{ Taking logarithm on both sides, we get  }\]
\[\log x = \frac{x}{y}\]
\[ \Rightarrow y\log x = x\]
\[ \Rightarrow \log x\frac{dy}{dx} + \frac{y}{x} = 1\]
\[ \Rightarrow \log x\frac{dy}{dx} = 1 - \frac{y}{x}\]
\[ \Rightarrow \log x\frac{dy}{dx} = \frac{x - y}{x}\]
\[ \Rightarrow x\log x\frac{dy}{dx} = x - y\]
\[ \Rightarrow \frac{dy}{dx} = \frac{x - y}{x\log x}\]

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Chapter 11: Differentiation - Exercise 11.05 [Page 90]

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RD Sharma Mathematics [English] Class 12
Chapter 11 Differentiation
Exercise 11.05 | Q 59 | Page 90

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