1/20+1/30+1/42······+1/132 简算 帮帮忙!

1/20+1/30+1/42······+1/132 简算 帮帮忙! 计算1/（1*4）+1/（4*7）+1/（7*10)+------+1/(97*100)································································································ 8+11+14+17+20+·······+305 数学计算题.呜呜呜1+2+3+4+···················+98+99+100+99+98+···············+3+2+1 阅读只管向前奔跑的答案1、文章开头四句诗有什么作用························································································ 1 2 3 4 ·····7 ·······10 ········?1 3 5 7 ·····?······?··········290 1 4 9 ·····?······?··········? 急·····················1+2+3+...+999=? 纸鹤数量的意义比如说 1只纸鹤,代表······· 2只纸鹤,代表······· ······················· ···························· ·················· 越多越好, 矩阵 求逆矩阵 1+a 1 1 ·····11 1+a 1·······1· · · ···························1 1 1 1+a 英语书 40 页 1a 人教版例如：down ·······································across··········································· 观察1/2 1/6 1/12 1/20 1/30·····的排列顺序,第60个数是多少?观察1/2 1/6 1/12 1/20 1/30··························的排列顺序,第60个数是多少? 在等腰三角形ABC中,AB=AC.求证1、∠BAD=∠CAE 2、如果AD=AE,那么BD=CE吗?急啊························································· “亲热、和善、拘束、惊恐”的近义词和反义词!速度····················1!·······111111111~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. 1怎么会等于0.999999999··········? 1+2++3+··········+10000= 人到底是不是动物1·········· 自封天下第一的动物··········!1 1+2+3+4+5+6+7+8+9+1+11+12+13+14+15````````1+2+3+4+5+6+7+8+9+1+11+12+13+14+15+16+17+18+19+20+21+22+23+24+25+26+27+28++29+30+31+32+33+34+35+36+37+38+39+40+41+42+43+44+45+46+47+48+49+50·································· 为什么0.999999······=1?