1/5+1/10+1/20+···+1/160 简便方法计算

1 2 3 4 ·····7 ·······10 ········?1 3 5 7 ·····?······?··········290 1 4 9 ·····?······?··········? 计算1/（1*4）+1/（4*7）+1/（7*10)+------+1/(97*100)································································································ 这几道奥数题谁会,求2014在哪一行那一列 1 2 3 4 5 10 9 8 7 6 11 12 13 14 15 20 19 18 17 16 求2014哪一行那一列 1 2 3 4 5 6 7 8 9 ···· ····· ·························· 1/5+1/10+1/20+···+1/160 简便方法计算 把自然数从1开始,排列成下表：1 2 4 7 11 16······ 3 5 8 12 17······ 6 9 13 18·····把自然数从1开始,排列成下表：1 2 4 7 11 16······3 5 8 12 17······6 9 13 18······10 14 19······15 20·· 序列 1 2 3 4 5 6 ······ n 对应的数 1 3 6 10 21······? 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 把这些数字由基数词变成序数词1·2·3·4·5·6·7·8·9·10·11·12·20·30·40·50·60·70·80·90·21·35·78 带有数字的四字词语按顺序1···2···3···4···5···6···7···8···9···10···祝福语 找规律:1·5·11·10·21·15·31·()·()急 1/20+1/30+1/42······+1/132 简算 帮帮忙! 1/(1×5)+1/(5×10)+1/(10×15)+···+1/(2005×2010)= 矩阵 求逆矩阵 1+a 1 1 ·····11 1+a 1·······1· · · ···························1 1 1 1+a 1+2+3+4+5·····+20 证明1·3·5·····(2n-1)/2·4·6·····2n 计算：|1/4-1/3|+|1/5-1/4|+|1/6-1/5|+······+|1/20-1/19| 正整数按图的规律排列,请写出第二十行,第二十一列的数 列 行 1 2 5 10 17 4 3 61118 9 8 7 12 19 急列 1 2 3 4 5行 1 2 5 10 17······················ 4 3 6 11 18······················9 俗语和名句的填空1······,自知之明.2······,行必果.3工欲善其事,······.4临渊羡鱼,······.5非学无以广才,······.6······,福兮祸之所伏.7项庄舞剑,······.8······,人以群