设所求两根为x3,x4
由题可知X1＋X2＝-b/a
x1x2=c/a
x3+x4=b/c
x3x4=a/c
所以x3+x4=-(x1+x2)/x3x4
x3x4=1/x1x2
所以x3=-1/x1;x4=-1/x2