裂项法计算:4/1*3-8/3*5+12/5*7-16/7*9+.+40/19*21 (*为乘号)
问题描述:
裂项法计算:4/1*3-8/3*5+12/5*7-16/7*9+.+40/19*21 (*为乘号)
答
4/1*3-8/3*5+12/5*7-16/7*9+....+40/19*21
=1+1/3-1/3-1/5+1/5+1/7-1/7-1/9+……+1/19+1/21
=1+1/21
=1又1/21
答
4/1*3-8/3*5+12/5*7-16/7*9+.+40/19*21
=1+1/3-1/3-1/5+1/5+1/7-1/7-1/9+……+1/19+1/21
=1+1/21
=1又1/21