Question

Помогите, пожалуйста. Даю 30 баллов.

НОМЕР 11.

Answer 1

$lny+\frac{x}{y}-a=0\\\frac{\partial f}{\partial x}=\frac{1}{y}\\\frac{\partial f}{\partial y}=\frac{1}{y}-\frac{x}{y^2}=\frac{y-x}{y^2}\\f'=\frac{\frac{\partial f}{\partial x}}{\frac{\partial f}{\partial y}}=\frac{\frac{1}{ y}}{\frac{y-x}{y^2}}=\frac{y}{ y-x}$