计算:1/1x2+1/2x3+1/3x4+.+1/(n-1)n
一道简便计算数学题1X2+2X3+3X4+4X5...+n(n+1)一1X2+2X3+3X4+4X5...+2013X2
1/1x2+1/2x3+1/3x4+...+1/n(n+1)怎么算
求使1x2+2x3+3x4+…+n(n+1)
已知无穷数列1x2,2x3,3x4…,n(n+1),… 求:
1x2+2x3+3x4+...+n(n+1)=?
1 总体X~N(2,4),X1,X2,X3,X4为样本,则(X1+X2+X3+X4)/4~( )
根据式子n(n+1)分之1=n(n+1)分之(n+1)-n=n分之1-n+1分之1计算1x2分之1+2x3分之1+3x4
X1,X2,X3,X4是总体N(0,1)的样本,则: X1-X2+X3-X4服从什么分布?
求线性方程组 x2-x3-x4=0 x1+x2-x3+3x4=1 x1-x2+x3+5x4=-1 x1+2x2-2x3+
(x1,x2,x3,x4,x5,x6)来自正态总体N(0,1),Y=(x1+x2+x3)^2+(x4)^2+(x5)^2
1+2x4-(x2+2x3)
X1+2X2-X3+X4=1