1x2+2x3+3x4+4x5+.+15x16

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1x2+2x3+3x4+4x5+.+15x16

1x2+2x3+3x4+4x5+.+15x16
1x2+2x3+3x4+4x5+.+15x16

1x2+2x3+3x4+4x5+.+15x16
可看成通项公式an=n×(n+1)的前15项之和,
前n项和Sn=1×2+2×3+3×4+4×5+……+n×(n+1)
=(1^2+1)+(2^2+2)+(3^2+3)+…+(n^2+n)
=(1^2+2^2+3^2+…+n^2)+(1+2+3+…+n)
=1/6×n(n+1)(2n+1)+1/2×n(n+1)
=1/6×n(n+1)(2n+1+3)
=1/3×n(n+1)(n+2)
∴1×2+2×3+3×4+4×5+……+15×16=1/3×15×16×17=1360

由1X2=1/3X1X2X3;
1X2+2X3=1/3X2X3X4
1X2+2X3+3X4=1/3X3X4X5
得出1/3*n*(n+1)*(n+2)
1x2+2x3+3x4+4x5+......+15x16=1/3X15X16X17=1360

1x2+2x3+3x4+4x5+.+15x16 x1-x2+x3=1 x2-x3+x4=2 x3-x4+x5=3 x4-x5+x1=4 x5-x1+x2=5 求x1,x2,x3,x4,x5 求非齐次线性方程组的通解x1+3x2+5x3-4x4=1x1+3x2+2x3-2x4+x5=-1x1-2x2+x3-x4-x5=3x1+2x2+x3-x4-x5=3 若x1,x2,x3,x4,x5满足方程组:x1-x2+x3=1 x2-x3+x4=2 x3-x4+x5=3 x4-x5+x1=4 x5-x1+x2=5 求x2,x3,x4的少打了个字,是求x2,x3,x4的值 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 1x2+2x3+3x4+4x5...+15x16,结果是奇数还是偶数? x1-x2+x3=1x2-x3+x4=21若x1,x2,x3,x4,x5满足方程组 x3-x4+x5=3x4-x5+x1=4x5-x1+x2=5求x2 x3 x4的值2已知 x1+x4+x6+x7=39 x2+x4+x5+x7=49 x3+x5+x6+x7=41 x4+x7=13 x5+x7=14 x6+x7=9 x1+x2+x3+x4+x5+x6+x7=9求x7的值若x1,x2,x3,x4,x5满足方程组 x1-x 求非其次线性方程组 {x1+2x2+x3+x4+x5=1x1+2x2+x3+x4+x5=12x1+4x2+3x3+x4+x5=2-x1-2x2+x3+3x4-x5=5 2x3+4x4-2x5=6 的一般解 解方程组:x1+x2+x3+x4+x5=7 3x1+2x2+x3+x4-3x5=-2 x2+2x3+2x4+6x5=23 5x1+4x2-3x3+3x4-x5=10 matlab线性方程组计算X1+X2-5X3-X4+X5=98X1+5X2-X3+4X5=23X1-7X2-5X3-X4+X5=42X1+X2+8X3+3X4-X5=-86X2+2X3+7X4-2X5=15 求方程组x1+3x2+x3+2x4+4x5=3 2x1-x2+8x3+7x4+2x5=9 4x1+5x2+6x3+11x4+10x5=15的全部解线性代数 求线性方程组的全部解,并用对应导出组的基础解系表示X1+3X2+5X3-4X4=1 X1+3X2+2X3-2X4+X5=-1 X1-2X2+X3-X4-X5=3 X1-4X2+X3+X4-X5=3 X1+2X2+X3-X4+X5=-1 简算:1/1x2+1/2x3+1/3x4+1/4x5 1/1x2 + 1/2x3 + 1/3x4 + 1/4x5 已知数据x1,x2,x3,x4,x5的平均数是20,那么另一组数据x1,x2+1,x3+2,X4+3,X5+4的平均数 求下列非齐次线性方程组的通解(1){x1+x2+x3+x4+x5=2;x1+2x2-4x5=-2;x1+2x3+2x4+6x5=6;4x1+5x2+3x3+3x4-x5=4}(2){x1-x2+5x3-x4=1;x1+x2-2x3+3x4=1;2x1+3x3+2x4=2;2x1+4x2-11x3+10x4=2}(3){x1+x2+x3+x4+x5=1;3x1+2x2+x3+x4-3x5=0 求解线性方程组 x1-2x2+3x3-x4-x5=2 x1+x2-x3+x4-2x5=1 2x1-求解线性方程组x1-2x2+3x3-x4-x5=2x1+x2-x3+x4-2x5=12x1-x2+x3-2x5=22x1+2x2-5x3+2x4-x5=5 简算.1/1X2+1/2X3+1/3X4+1/4X5+.+1/199X200, 1x2/1+2x3/1+3x4/1+4x5/1+…+39x40/1