1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90+1/110=多少的简便运算怎么还没来答案
2019-04-15
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90+1/110=多少的简便运算
怎么还没来答案
优质解答
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90+1/110
=1/(1×2)+1/(2×3)+1/(3×4)+...+1/(10×11)
=1-1/2+1/2-1/3+1/3-1/4+...+1/10-1/11
=1-1/11
=10/11
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90+1/110
=1/(1×2)+1/(2×3)+1/(3×4)+...+1/(10×11)
=1-1/2+1/2-1/3+1/3-1/4+...+1/10-1/11
=1-1/11
=10/11