MCQ
If ${x^2}{e^{y\,}}\, + \,2xy{e^{x\,}}\, + 13\, = \,0$, then $\frac{{dy}}{{dx}}$ equals
  • $- \frac{{2x{e^{y - x}} + 2y(x + 1)}}{{x(x{e^{y - x}} + 2)}}$
  • B
    $ \frac{{2x{e^{x - y}} + 2y(x + 1)}}{{x(x{e^{y - x}} + 2)}}$
  • C
    $- \frac{{2x{e^{x - y}} + 2y(x + 1)}}{{x(x{e^{x - y}} + 2)}}$
  • D
    None of these

Answer

Correct option: A.
$- \frac{{2x{e^{y - x}} + 2y(x + 1)}}{{x(x{e^{y - x}} + 2)}}$
a
Using partial derivatives, we have

$\frac{d y}{d x} =-\frac{2 x e^{y}+2 y e^{x}+2 x y e^{x}}{x^{2} e^{y}+2 x e^{x}} $

$=-\frac{2 x e^{y-x}+2 y+2 x y}{x^{2} e^{y-x}+2 x} $

$=-\frac{2 x e^{y-x}+2 y(x+1)}{x\left(x e^{y-x}+2\right)}$

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