dy/dx = 2xy^2 ==> dy/y^2 = 2x dx ==> ∫ dy/y^2 = ∫ 2x dx ==> -1/y = x^2 + C ==> 1/y^2 = x^4 + 2C*x^2 + C^2 ==> ∫ dx/y^2 = ∫ (x^4 + 2C*x^2 + C^2) dx ==> ∫ dx/y^2 = x^5 / 5 + 2C*x^3 / 3 + C^2 * x + D C、D为任意常数