8.【线性代数】——求解Ax=b求解 { x 1 + 2 x 2 + 2 x 3 + 2 x 4 = b 1 2 x 1 + 4 x 2 + 6 x 3 + 8 x 4 = b 2 3 x 1 + 6 x 2 + 8 x 3 + 10 x 4 = b 3 \begin{cases} x_1 +2x_2 + 2x_3+2x_4 = b_1 \\ 2x_1 +4x_2 + 6x_3+8x_4 = b_2\\ 3x_1 +6x_2 + 8x_3+10x_4 = b_3\\ \end{cases} ⎩ ⎨ ⎧x1+2x2+2x3+2x4=b12