1x2÷1+2x3÷1+3x4÷1+4x5÷1+5x6÷1等于?
1x1-2x2+3x3-4x4+5x5-6x6.-100x100+101x101
x8+x7+x6+x5+x4+x3+x2+x+1因式分解
1/1X2+1/2X3+1/3X4+1/4X5+1/5X6……1/2007X2008
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
(2X2)/1X3+(4X4)/(3X5)+(6X6)/(5X7)+...+(20X20)/(19X21)==?
解方程组X2+X3+X4=1 X1+X2+X3=5 X3+X4+X5=-5 X4+X5+X1=-3 X5+X1+X2=2
84÷63X3 1X5.3+2.1X6.2-2.1X1.5
(x1,x2,x3,x4,x5,x6)来自正态总体N(0,1),Y=(x1+x2+x3)^2+(x4)^2+(x5)^2
求齐次线性方程组x1+2x2+x3+x4+x5=1 2x1+4x2+3x3+x4+x5=2 -x1-2x2+x3+3x4
1x2+2x4+3x6+4x8 ------------------------------- 2x3+4x6+6x9+