方程的根是：x=[-b±√(b²-4ac)]/2a
∴x1+x2=[-b+√(b²-4ac)]/2a+[-b-√(b²-4ac)]/2a=-2b/2a=-b/a
方程两个根是m与n,∴m+n=-(-3)/1=3最后题目的答案是？能分行详细的说吗?是2001吗∵a=1 b=-3∴x1+x2=-b/a=-(-3)/1=3即m+n=3