matlab中，老提示这个错误的原因是什么？求大神解决

syms x ;
S=dsolve('Dy=((60-x)/y-(y/(x^2+y^2-60*x))*(2*75*(80+400*(60-x/y))*400/(10000-50*(600-((x^2+y^2-60*x)/y)))+60))/(1+(60-x)/y*(y/(x^2+y^2-60*x))*(2*75*(80+400*(60-x/y))*400/(10000-50*(600-((x^2+y^2-60*x)/y)))+60))','y(0)=-600','x');
x=S.x
y=S.y
hold on;
ezplot(x);
ezplot(y);

??? Error using ==> dsolve
Error, (in dsolve/IC) The 'implicit' option is not available when giving Initial Conditions.

---

无解的方差，不赋初值一茄氏和样解不出来
警颤盯告的核友含义：表达式太复杂

dsolve('Dy=((60-x)/y-(y/(x^2+y^2-60*x))*(2*75*(80+400*(60-x/y))*400/(10000-50*(600-((x^2+y^2-60*x)/y)))+60))/(1+(60-x)/y*(y/(x^2+y^2-60*x))*(2*75*(80+400*(60-x/y))*400/(10000-50*(600-((x^2+y^2-60*x)/y)))+60))');
Warning: Explicit solution could not be found; implicit solution returned.

---