第一题：原式左= (2xydx + x^2dy) + cosydy = d(x^2 * y) + d(Siny) = d(X^2 * y + Siny) = 0所以通解为x^2 * y + siny = C,C为常数第二问：变形为dy / dx = (y^2 - y) * sinx dy / (y-1)y = dx * sinx[1/(y-1) - 1/...