3S^4+18S^3+30S^2+18S+3=0 没分了,

3S^4+18S^3+30S^2+18S+3=0 S^4+6S^3+10S^2+6S+1=0S^4+S^3+5S^3+5S^2+5S^2+5S+S+1=0S^3(S+1)+5S^2(S+1)+5S(S+1)+(S+1)=0(S+1)(S^3+5S^2+5S+1)=0S1=-1S^3+5S^2+5S+1=0S^3+S^2+4S^2+4S+S+1=0(S^3+S^2)+(4S^2+4S)+(S+1)=...