1/1x3+1/2x4+1/3x5+1/4x6+...+1/100x102=?
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1/1x3+1/2x4+1/3x5+1/4x6+...+1/100x102=?
∵2*【1/1x3+1/2x4+1/3x5+1/4x6+...+1/100x102】
=1/1-1/3+1/2-1/4+1/3-1/5+1/4-1/6+.+1/99-1/101+1/100-1/102
=1+1/2-1/101-1/102
=(101*102+101*51-102-101)/101*102
=15250/10302
=7625/5151
∴ 1/1x3+1/2x4+1/3x5+1/4x6+...+1/100x102=12=7625/10302
=1/1-1/3+1/2-1/4+1/3-1/5+1/4-1/6+.+1/99-1/101+1/100-1/102
=1+1/2-1/101-1/102
=(101*102+101*51-102-101)/101*102
=15250/10302
=7625/5151
∴ 1/1x3+1/2x4+1/3x5+1/4x6+...+1/100x102=12=7625/10302
1x1-2x2+3x3-4x4+5x5-6x6.-100x100+101x101
1/2x4十1/4x6十…十1/100X102
x8+x7+x6+x5+x4+x3+x2+x+1因式分解
(2X2)/1X3+(4X4)/(3X5)+(6X6)/(5X7)+...+(20X20)/(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
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
求齐次线性方程组x1+2x2+x3+x4+x5=1 2x1+4x2+3x3+x4+x5=2 -x1-2x2+x3+3x4
解方程组X2+X3+X4=1 X1+X2+X3=5 X3+X4+X5=-5 X4+X5+X1=-3 X5+X1+X2=2
1x2+2x4+3x6+4x8 ------------------------------- 2x3+4x6+6x9+