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If \({\mathrm{xe}}^{\mathrm{y}}=1\), then the value of \(\frac{\mathrm{dy}}{\mathrm{d}x}\) at \(\mathrm{x}=1\) is :

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If \({\mathrm{xe}}^{\mathrm{y}}=1\), then the value of \(\frac{\mathrm{dy}}{\mathrm{d}x}\) at \(\mathrm{x}=1\) is :

a

-1

b

1

c

\(-e\)

d

\(-\frac{1}{e}\)

✓ Correct answer: a)

-1

Explanation

\(\frac{d}{dx}\left(x{e}^{y}\right)=\frac{d}{dx}(1)\)

\({e}^{y}+x{e}^{y}\frac{dy}{dx}=0\)

\(\frac{dy}{dx}=\frac{-{e}^{y}}{x{e}^{y}}\)

\(\frac{dy}{dx}=-\frac{1}{x}\)

\({\left.\frac{dy}{dx}\right|}_{x=1}=-\frac{1}{1}=-1\)

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