y=xtanx+C
y=xtan(C-x)
The given differential equation is \( y - x y' = x^2 + y^2 \).
We can solve this differential equation by using an appropriate substitution or method, such as separating variables or an integrating factor. However, we recognize that this is a first-order non-linear differential equation, and we will attempt a suitable transformation.
By trial and error or using the standard methods for solving such equations, we find that the solution is of the form:
\( y = x \tan(x) + C \).
The correct answer is \( y = x \tan(x) + C \).
Let $ y(x) $ be the solution of the differential equation $$ x^2 \frac{dy}{dx} + xy = x^2 + y^2, \quad x > \frac{1}{e}, $$ satisfying $ y(1) = 0 $. Then the value of $ 2 \cdot \frac{(y(e))^2}{y(e^2)} $ is ________.