1/6+1/12+1/20+1/30+1/42+1/56等于多少?

1/6+1/12+1/20+1/30+1/42+1/56等于多少?
1/6+1/12+1/20+1/30+1/42+1/56等于多少?

1/6+1/12+1/20+1/30+1/42+1/56等于多少?
=1/2×3+1/3×4+1/4×5+1/5×6+1/6×7+1/7×8
=1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8
=1/2-1/8
=3/8

1/6+1/12+1/20+1/30+1/42+1/56
=1/2*3+1/3*4+1/4*5+1/5*6+1/6*7+1/7*8
=1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8
=1/2-1/8
=4/8-1/8
=3/8

1/6+1/12+1/20+1/30+1/42+1/56
=1/(2×3)+1/(3×4)+1/(4×5)+1/(5×6)+1/(6×7)+1/(7×8)
=1/2 -1/3 +1/3 -1/4 +1/4 -1/5 +1/5 -1/6 +1/6 -1/7 +1/7 -1/8
=1/2 -1/8
=3/8谢谢你！谢谢你！ 谢谢你！谢谢你！