1/1X2+1/2x3+1/3x4+1/4x5+.+1/98x99+1/99x100求结果!
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1/1X2+1/2x3+1/3x4+1/4x5+.+1/98x99+1/99x100求结果!1/1X2+1/2x3+1/3x4+1/4x5+.+1/98x99+1/99x100求结果!1/1X2+1/
1/1X2+1/2x3+1/3x4+1/4x5+.+1/98x99+1/99x100求结果!
1/1X2+1/2x3+1/3x4+1/4x5+.+1/98x99+1/99x100求结果!
1/1X2+1/2x3+1/3x4+1/4x5+.+1/98x99+1/99x100求结果!
1/[n(n+1)]=1/n - 1/(n+1)
原式=1/1 - 1/2 + 1/2 - 1/3 +…+1/99 - 1/100
=1- 1/100
=0.99
1/1X2+1/2x3+1/3x4+1/4x5+......+1/98x99+1/99x100=
1-1/2+1/2-1/3+1/3-1/4.....+1/99-1/100
=1-1/100
=99/100
1/1X2+1/2x3+1/3x4+1/4x5+......+1/98x99+1/99x100=
1-1/2+1/2-1/3+1/3-1/4.....+1/99-1/100
=1-1/100
=99/100
易证1/[n(n+1)]=1/n - 1/(n+1)
所以 原式=1/1 - 1/2 + 1/2 - 1/3 +…+1/99 - 1/100
=1- 1/100
=0.99
1/n(n+1)=1/n -1/(n+1),则原式=1-1/2+1/2-1/3+......+1/98-1/99+1/99-1/100=1-1/100=99/100
1/1乘2等于1/1减1/2 同理2乘3分之一等于2分之一减去3分之一 上式等于1/1-1/2+1/2--1/3+1/3......-1/99+1/99-1/100等于99/100
因式分解：x4+x3+2x2 +x+1
用克拉默法则解下列方程组 x1-2x2+3x3-4x4=4 x2-x3+x4=-3 x1+3x2+2x4=1 -7x2+3x3+x4=3x1-2x2+3x3-4x4=4x2-x3+x4=-3 x1+3x2+2x4=1 -7x2+3x3+x4=3
解方程组X1-2x2+3x3-x4=1,3x1-x2+5x3-3x4=2,2x1+x2+2x3-2x4=3
x1+5x2-x3-x4=-1x1-2x2+x3+3x4=33x1+8x2-x3+x4=1
写出方程组2*x1+x2-x3+x4=1,x1+2*x2+x3-x4=2,x1+x2+2*x3+x4=3的通解?
求非齐次线方程组的通解 ：2x1+x2-x3+x4=1 x1+2x2+x3-x4=2 x1+x2+2x3+x4=3
具体写出方程组：2x1+x2-x3+x4=1;x1+2x2+x3-x4=2;x1+x2+2x3+x4=3的通解
解一道方程组x1+x2+x3=5,x2+x3+x4=1,x3+x4+x5=-5,x4+x5+x1=-3,x5+x1+x2=2
用初等行变换来解下列线性方程组（1）2x1-x2+3x3=3 3x1+x2-5x3=0 4x1-x2+x3=3 x1+3x2-13x3=-6(2) x1-2x2+x3+x4=1 x1-2x2+x3-x4=-1 x1-2x2+x3-5x4=5(3) x1-x2+x3-x4=1 x1-x2-x3+x4=0 x1-x2-2x3+2x4=-1/2
1X2+2X3+3X4+.NX(N+1)
1X2+2X3+3X4+.NX(N+1)规律
1x2+2x3+3x4+.+2011x2012
1x2+2x3+3x4+4x5+.+15x16
1x2+2x3+3x4+.+100x101=
1x2+2x3+3x4+.+100x101=?结果
1x1!+2x2!+3x3!+4x4!.nxn!
1X2+2x3+3x4+……+2013x2014
1x2+2x3+3x4+.+19x20