2+（-4）+6+（-8）+····+46+（-48）+50等于多少都不对

（1+3+5++7+9······+2011）-（2+4+6+8······+2012）= 下列算式中的被除数相同,怎么填（ ）/3=（ ）········2 （ ）/6=（ ）······2 （ ）/4=（ ）·····2 （ ）/8=（ ）···2 1/（2*4）+1/（4*6）+1/（6*8）+········+1/（2006*2008）等于? 计算1/（1*4）+1/（4*7）+1/（7*10)+------+1/(97*100)································································································ （|+3+5+7+···+2013）—（2+4+6+8···）=? 求（2+5+8······+2000）-（1+4+7······+1999）的值.【简算】 （1+3+5+······2013）—（2+4+6······+2014）用简便方法哦,这是奥数题. 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 (2)上表中每列三个数分别是(4,3,5),(6,8,10)···（1）按规律填表4 6 8 ··· 2n ···3 8 15 ···（ ） ···5 10 17 ···（ ）···（2)上表中每列三个数分别是(4,3,5),(6,8,10),（8,15,17）··每组数 （ 28 ＋ 7分之2 × 8分之7 ） × 4分之1 ＝ ? 高·手·进······················快·快·快·快·快·快·快·快·快·快·快·快·快·快·快·快·快·快·快·快·快·快·快·快·快·快·快·快 求一道数学题：脱式简便计算（1+3+5+7+······+2011）-（2+4+6+8+······+2010） 用简便方法计算（2+4+6+8······+2014）—（1+3+5+7······+2013） 根据1+2+3+4+······+n=n(n+1）/2 计算2+4+6+····+200 2[4/3y—（2/3y—1/2）]=3/4y急·································!1 为什么 3分之2+3分之4=2 而3分之2等于0.666······（6循环） 3分之4等于1.333······（3循环）0.666······（6循环）+1.333······（3循环） =1.999······（9循环）而不等于2? （-1）×2×（-3）×4×···×（-49）×50/2×4×6×···×100 2011红领巾快乐数独答案一2·····4·9·631·4·8·8··97··3··3··2·95···95·86···15·3··7··9··47··5·7·3·182·3·4·····7二7·1·8·3·····413·6·2·6···4·8·8·5·1·2·61·····94·2·9·4·7·8· 观察下列三角形数表其中从第二行起每行的每一个数为其肩膀上两树之和则该表的最后一个数是?1 2 3 4 5 6 7 8················ 97 98 99 100 3 5 7··························