是否有解: 求解一下方程组: ⎧⎩⎨⎪⎪x1+2x2+2x3+2x4=b12x1+4x2+6x3+8x4=b23x1+6x2+8x3+10x4=b3{ x1+2x2+2x3+2x4=b12x1+4x2+6x3+8x4=b23x1+6x2+8x3+10x4=b3 写出增广矩阵,然后使用消元法来解: ⎡⎣⎢⎢