1/1x3+1/2x4＋1/3x5＋1/4x6＋……＋1/19x21 急,

来源：学生作业帮编辑：大师作文网作业帮分类：数学作业时间：2024/11/18 12:48:21

1/1x3+1/2x4＋1/3x5＋1/4x6＋……＋1/19x21=((1-1/3)+(1/2-1/4)+(1/3-1/5)+……+(1/19-1/21))*0.5=(1+1/2-1/20-1/21)*0.5=589/840

(2X2)/1X3+(4X4)/(3X5)+(6X6)/(5X7)+...+(20X20)/(19X21)==? 1/1X2+1/2X3+1/3X4+1/4X5+1/5X6……1/2007X2008 1x1-2x2+3x3-4x4+5x5-6x6.-100x100+101x101 x8+x7+x6+x5+x4+x3+x2+x+1因式分解 1x2/1+2x3/1+3x4/1+4x5/1+5x6/1+6x7/1 1/1x2+1/2x3+1/3x4+1/4x5+1/5x6+......1/2008x2009 1/1x2+1/2x3+1/3x4+1/4x5+1/5x6+1/6x7 计算(1+1／1x3)(1+1／2x4）（1+1／3x5）（1+/4x6）……(1+/11×13) 2/1X3+2/3X5+2/5x7+.+2/19x21 (x1,x2,x3,x4,x5,x6)来自正态总体N(0,1),Y=(x1+x2+x3)^2+(x4)^2+(x5)^2 求解一个方程急 X（1次方）+X2+X3=5 X2+X3+X4=1 X3+X4+X5=-5 X4+X5+X1=-3 X5 1x2+2x4+3x6+4x8 ------------------------------- 2x3+4x6+6x9+