Question

Помогите решить, плииииз, сроочно

Answer 1

$\displaystyle \dfrac{xdx+ydy}{\sqrt{x^2+y^2}}=\dfrac{ydx-xdy}{x^2}~~~\Rightarrow~~~\dfrac{d(\frac{x^2}{2}+\frac{y^2}{2})}{\sqrt{x^2+y^2}}=d\left(\dfrac{y}{x}\right)\\ \\ \\ \int\dfrac{d(x^2+y^2)}{2\sqrt{x^2+y^2}}=\int d\left(\dfrac{y}{x}\right)~~~\Rightarrow~~~ \boxed{\sqrt{x^2+y^2}=\dfrac{y}{x}+C}$