1x2+2x3+3x4+…+10x11=?
来源:学生作业帮 编辑:搜搜做题作业网作业帮 分类:数学作业 时间:2024/08/19 19:56:14
1x2+2x3+3x4+…+10x11=?
1x2=1/3(1x2x3-0x1x2)
2x3=1/3(2x3x4-1x2x3)
3x4=1/3(3x4x5-2x3x4)
1x2+2x3+3x4=1/3x3x4x5=20
1x2+2x3+3x4+…+n(n+1)=?《2010汕头中考》
1x2x3+2x3x4+3x4x5+....+7x8x9=?
1x2=1/3(1x2x3-0x1x2)
2x3=1/3(2x3x4-1x2x3)
3x4=1/3(3x4x5-2x3x4)
1x2+2x3+3x4=1/3x3x4x5=20
1x2+2x3+3x4+…+n(n+1)=?《2010汕头中考》
1x2x3+2x3x4+3x4x5+....+7x8x9=?
1x2+2x3+3x4+…+n(n+1)
=1x(1+1)+2x(2+1)+3x(3+1)+…n(n+1)
=(1^2+2^2+3^2+…+n^2)+(1+2+3+…+n)
=n(n+1)(2n+1)/6+n(n+1)/2
=n(n+1)[(2n+1)+3]/6
1x2+2x3+3x4+…+10x11
=10x(10+1)x[(10x2+1)+3]/6
=110x4
=440
=1x(1+1)+2x(2+1)+3x(3+1)+…n(n+1)
=(1^2+2^2+3^2+…+n^2)+(1+2+3+…+n)
=n(n+1)(2n+1)/6+n(n+1)/2
=n(n+1)[(2n+1)+3]/6
1x2+2x3+3x4+…+10x11
=10x(10+1)x[(10x2+1)+3]/6
=110x4
=440
1x2+2x3+3x4+4x5+……+10x11
2x2/1x3+4x4/3x5+6x6/5x7+8x8/7x9+10x10/9x11+12x12/11x13 仔细看看
求线性方程组 x2-x3-x4=0 x1+x2-x3+3x4=1 x1-x2+x3+5x4=-1 x1+2x2-2x3+
求齐次线性方程组{X1+X2+3X3+2X4=0 2X1+3X2+X3-X4=0 5X1+6X2+10X3+5X4=0}
求齐次线性方程组x1+2x2+x3+x4+x5=1 2x1+4x2+3x3+x4+x5=2 -x1-2x2+x3+3x4
设线性方程组(x1+2x2-2x3+2x4=2,x2-x3-x4=1 x1+x2-x3+3x4=a)
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
解方程组X2+X3+X4=1 X1+X2+X3=5 X3+X4+X5=-5 X4+X5+X1=-3 X5+X1+X2=2
X1+2X2-X3+X4=1
求非齐次线性方程组:2x1-x2+4x3-3x4=-4;x1+x3-x4=-3;3x1+x2+x3=1;7x1+7x3-
1分解因式:2x4-x3-13x2-15=?2.分解因式:x5+x4+x3+x2+x+1=?3分解因式:x4-4x2+6
用列主元Gauss消元法解线性方程组{-x2-x3+x4=0,x1-x2+x3-3x4=1,2x1-2x2-4x3+6x