观察2=1x2,2+4=2x3,2+4+6=3x4···计算2+4+6+·····+2n的公式

解方程组 X1-X2-4X3=-1 X2+X3=2 X1+X2-2X3=3线性代数 maxz=3x1+4x2+x3 -1+2x2+3x3 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 max Z=2X1+4X2-5X3 X1+X2+X3=7 2X1-3X2+X3≥10 X1.X2.X3≥0 ｛2X1-X2+3X3=33X1+X2-5X3=04X1-X2+X3=3X1+3X2-13X3=-6{X1-2X2+3X3-4X4=4X2-X3+X4=-3X1+3X2-3X4=1-7X2+3X3+X4=-3 求解线性方程组 2X1+X2-X3+X4=1 4X1+2X2-2X3+2X4=2 2X1+X2-X3-X4=1 的通解 求非齐次线性方程组的通解：2x1+x2-x3-x4=1;2x1+x2+x3-x4=1;4x1+2x2+x3-2x4=2 求下列线性方程组的通解：2x1+x2-x3+x4=1,4x1+2x2-2x3+x4=2,2x1+x2-x3-x4=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 线性方程组 X1+X2+X3+X4=0,2X1+X2+X3+2X4=0,3X1+2X2+4X3+4=1 求线性方程组-2X1+X2+X3=1 X1-2X2+X3=-2 X1+X2-2X3=4 的一般解 求解线性方程组-x1+x2+2x3=1;x1-x2+x3=2;5x1-5x2-4x3=1 利用逆矩阵解方程x1-x2+x3=1,-2x1-x2-2x3=3,4x1+3x2+3x3=-1 X1-X2+X3-X4=1X1-X2-X3+X4=02X1-2X2-4X3+4X4=-1麻烦高人用高斯消元法解下这个方程 解方程组x1+x2=4,x2+x3=-6,x3+x1=2 2x3+4x- x2-(x+x2-2x3) ,其中x= -3 解线性方程组 x1-x2-x3=2 x1+x2+4x3=0 3x1+5x3=3 mathematica如何求解含有三角函数的方程?FindRoot[{3 x1^3 + 2 x2 - 5 + Sin[x1 - x2] Sin[x1 + x2] == 0,-x1*Exp[x1 - x2] + x2 (4 + 3 x2^2) + 2 x3 + Sin[x2 - x3] Sin[x2 + x3] - 8 == 0,-x2*Exp[x2 - x3] + 4 x3 - 3 ==0},{x1,Pi/2},{x2,2},{x3,0}]