[填空题]
Consider the differe5m xad7x6t79 bq0*dgq eyu cf/votv o ))/nx-yntial equation $\frac{\mathrm{d} y}{\mathrm{~d} x}+\frac{2 x^{3}}{1+x^{4}} y=4 x^{3} $ where y=1 when x=0 .
1. Show that $\sqrt{1+x^{4}} $ is an integrating factor for this differential equation.
2. Solve the differential equation giving your answer in the form y=f(x) .
