1x2/3+2x3/3+3x4/3...+2003x2004/3

来源：学生作业帮助网 编辑：作业帮 时间：2024/11/17 05:32:25

1x2/3+2x3/3+3x4/3...+2003x2004/3
1x2/3+2x3/3+3x4/3...+2003x2004/3

1x2/3+2x3/3+3x4/3...+2003x2004/3
首先说明一下,当分式左右书写的时候,分子写在“/”左边,分母写在“/”右边.
如果本题写的是对的,3是分母：
考察一般项：
n(n+1)/3=(1/3)(n²+n)
1×2/3+2×3/3+...+2003×2004/3
=(1/3)[(1²+2²+...+2003²)+(1+2+...+2003)]
=(1/3)(2003×2004×4007/6 +2003×2004/2)
=(1/3)(2680691014+2007006)
=2682698020/3
用到的公式：
1²+2²+...+n²=n(n+1)(2n+1)/6
1+2+...+n=n(n+1)/2
对于本题,n=2003.
如果是分子分母写反了的话,3是分子：
3/(1×2)+3/(2×3)+...+3/(2003×2004)
=3[1/(1×2)+1/(2×3)+...+1/(2003×2004)]
=3(1-1/2+1/2-1/3+...+1/2003-1/2004)
=3(1-1/2004)
=2003/668

1×2在分母...
3/(1×2)+3/(2×3)+...+3/(2003×2004)
=3*(1-1/2+1/2-1/3+...+1/2003-1/2004)
=3*(1-1/2004)
=3*2003/2004
=2003/668

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 因式分解x4+x3+2x2-x+3 解方程组X1-2x2+3x3-x4=1,3x1-x2+5x3-3x4=2,2x1+x2+2x3-2x4=3 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 x1+5x2-x3-x4=-1x1-2x2+x3+3x4=33x1+8x2-x3+x4=1 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 非齐次线性方程组求解.x1+x2+2x3+3x4=1 2x1+3x2+5x3+2x4=-3 3x1-x2-x3-2x4=-4 3x1+5x2+2x3-2x4=-10 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