Question

线性代数，初等行变换，方程组求解

线性代数，初等行变换，方程组求解再如何往下算

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Answer 1

(A, b) 初等行变换为
[1 1 1 1 5]
[0 1 -2 3 -7]
[0 -5 -3 -7 -12]
[0 -2 -1 8 -15]
初等行变换为
[1 0 3 -2 12]
[0 1 -2 3 -7]
[0 0 -13 8 -47]
[0 0 -5 14 -29]
初等行变换为
[1 0 3 -2 12]
[0 1 -2 3 -7]
[0 0 2 -34 40]
[0 0 -5 14 -29]
初等行变换为
[1 0 0 49 -48]
[0 1 0 -31 33]
[0 0 1 -17 20]
[0 0 0 -71 71]
初等行变换为
[1 0 0 0 1]
[0 1 0 0 2]
[0 0 1 0 3]
[0 0 0 1 -1]
得 唯一解 x = (1, 2, 3, -1)^T