-(-(-…-(-1)···)-----2n+1个负号,n是整数

已知a1=2b a2=2/a1 a3=2/a2 ……a2008=2/a2007 求a1*a2008的积这是一道数学题,帮帮忙···记住a1不是a*1切忌··快啊······················································ 计算1/（1*4）+1/（4*7）+1/（7*10)+------+1/(97*100)································································································ 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, 英语书 40 页 1a 人教版例如：down ·······································across··········································· q1*q2*q3*q4……q(n-1) =怎么算,帮个忙······· 矩阵 求逆矩阵 1+a 1 1 ·····11 1+a 1·······1· · · ···························1 1 1 1+a 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························································· 三角形数和正方形数的规律比如（三）：1,3,6,10,15,21,……正：1,4,9,16,25·············· “亲热、和善、拘束、惊恐”的近义词和反义词!速度····················1!·······111111111~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. 如图是由点组成的三角形图案,每条边上有n个点（n大于1）,每个图案的总点数用s表示：· · · · · · · · · · · ·n=2 · · · · · · · ……n=3 · · · · · ·n=4 · · · · ·n=5（1）观察图案,当n=5 如下图,是由点组成的三角形图案,每条边上有n个点（n大于1）,每个图案的总点数用s表示：· · · · · · · · · · · ·n=2 · · · · · · · ……n=3 · · · · · ·n=4 · · · · ·n=5（1）观察图案,当n 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 1怎么会等于0.999999999··········? 1+2++3+··········+10000= 人到底是不是动物1··········