Question

1又1/2+2又1/6+3又1/12+4又1/20+5又1/30+6又1/42+7又1/56+8又1/72+9又1/90

Answer 1

原式=(1+2+...+10)+(1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90+1/110)

=10(10+1)/2+[(1-1/2)+(1/2-1/3)+...+(1/10-1/11)].(去括号)

=55+10/11