1/(7x9)+1/(9x11)+1/(11x13)+.+1/(33x35)=?请在问问里的人群们帮帮忙!虽然在这里面写上去看起来有些麻烦!但是还是拜托你们了!急用!

1/1x3+1/3x5+1/5x7+1/7x9+1/9x11=? 1/1x3+1/3x5+1/5x7+1/7x9+1/9x11=? 1/5x7+1/7x9+1/9x11+1/11x13+…+1/23x25 1x3分之一+3x5分之一+5x7分之一+7x9分之一+9x11分之一 1/1x3+1/3x5+1/5x7+1/7x9+1/9x11+1/11x13= 1/1x3,1/3x5,1/5x7,1/7x9,1/9x11的通项公式 1 / (5x7) +1 / (7x9) +1 / (9x11)+ 1 / (11x13)+ 1 / (13x15)不能只有答案, 1x2+2x3+3x4+4x5+5x6+6x7+7x8+8x9+9x10+10x11 2/1x3+2/3X5+2/5x7=2/7x9+2/9x11计算.. 有2道分数简便运算奥数题不会.1/2X5+1/3X5+1/8X11+.+1/20X23=?2002/1x3+2002/3X5+2002/5X7+2002/7X9+2002/9X11=? 已知1-1/3=2/1x3,计算1/1x3+1/3x5+1/5x7+1/7x9+1/9x11= 1/(1x3)+1/(3x5)+1/(5x7)+1/(7x9)+1/(9x11).1/(97x99)=多少?这个肯定得用简便方法,请指教. （1x3）分之1 + （3x5）分之1+ （5x7）分之1 + （7x9）分之1 +（9x11）分之1 1/3十1/3x5十1/5X7十1/7x9十1/9X11十1/11X13 1x2+2x3+3x4+4x5+5x6+6x7+7x8+8x9+9x10+10x11+ +nx(n+1)= 2X/1x3+2X/3x5+2X/5x7+2x/7x9+2x/9x11=10 x=? 下面各题对吗?把不对的改正过来.5-3x9分之7=2X9分之7=9分之14 11分之411分之2X6分之11X11分之6=1主要改哪里啊,5-3x9分之7,还2X9分之7 mathematic 程序问题Min= X1+ X2+ X3+ X4+ X5+ X6+ X7+ X8+ X9+ X10+ X11;X1+1>=9;X2+1>=9;X3+2>=9;X4+2>=3;X5+1>=3;X6+2>=3;X7+1>=6;X8+2>=12;X9+2>=12;X10+1>=7; X11+1>=7; X1>=0;X2>=0;X3>=0;X4>=0;X5>=0;X6>=0;X7>=0;X8>=0;X9>=0;X10>=0;X11>=0;