计算:2/1*3+3/3*6+4/6*10+5/10*15+……+10/45*55,怎么算,
问题描述：
计算:2/1*3+3/3*6+4/6*10+5/10*15+……+10/45*55,怎么算,
答
=2/3+1/2+1/15+1/30+6/15*21+7/21*28+8/28*36+9/36*45+10/45*55
=2/3+1/2+1/15+1/30+2/105+1/84+1/126+1/180+2/495
=
答
原式=1/1-1/3 +1/3-1/6 +1/6-1/10 +1/10-1/15 +…… +1/45-1/55
=1-1/55 =54/55