Question

yy''-(y')2=y4满足当x=0时,y=1;当x=0时,y'=o

Answer 1

很明显的,不含x型,二阶微分方程,令y'=t,y''=t*t'

y*t*t'-t^2=y^4

然后t*t'=(t^2)'/2令t^2=s

(y/2)*s'-s=y^4

然后用公式解即可,解的过程就不用说了吧