a/a是啥意思?是除以?是的话,因为m>0,所以2m>ma除以a+ma/(a+m)+b/(b+m)-c/(c+m)(相减通分)=[a(b+m)(c+m)+b(a+m)(c+m)-c(a+m)(b+m)]/[(a+m)(b+m)(c+m)]因为三角形ABC三边长是a ,b, c>0,且m为正数所以分母[(a+m)(b+m)(c+m)]>0又因为a(b+m)(c+m)+b(a+m)(c+m)-c(a+m)(b+m)=abc+abm+acm+am^2+abc+bam+bcm+bm^2-abc-cam-cbm-cm^2=abc+(abm+bam)+(am^2+bm^2-cm^2)因为a+b>c(三角形两边之和大于第三边)所以am^2+bm^2=(a+b)m^2>cm^2所以(am^2+bm^2-cm^2)>0abc+(abm+bam)>0所以a/(a+m)+b/(b+m)>c/(c+m)转载，我很素质，不过还是希望你给分