If $e^x+e^y=e^{x+y}$, then $\frac{d y}{d x}=$

If $e^x+e^y=e^{x+y}$, then $\frac{d y}{d x}=$
  1. $-e^{y-x}$
  2. $e^{x-y}$
  3. $-e^{x-y}$
  4. $e^{y-x}$

Solution

$e^x+e^y=e^{x+y} \Rightarrow e^x+e^y \cdot \frac{d y}{d x}=e^{x+y}\left(1+\frac{d y}{d x}\right)$ $\Rightarrow \frac{d y}{d x}=\frac{e^x-e^{x+y}}{e^{x+y}-e^y}=\frac{e^x-e^x-e^y}{e^x+e^y-e^y}=-\frac{e^y}{e^x}=-e^{y-x}$

Asked in: MHT CET 2022 (07 Aug Shift 2)

Practice more Differentiation questions on Aicharya