Đại số tuyến tính Ví dụ

$[\begin{array}{c} 0 & 1 & 5 & - 4 \\ 1 & 4 & 3 & - 2 \\ 2 & 7 & 1 & - 2 \end{array}]$

Bước 1

Swap $R_{2}$ with $R_{1}$ to put a nonzero entry at $1, 1$ .

$[\begin{array}{c} 1 & 4 & 3 & - 2 \\ 0 & 1 & 5 & - 4 \\ 2 & 7 & 1 & - 2 \end{array}]$

Bước 2

Perform the row operation $R_{3} = R_{3} - 2 R_{1}$ to make the entry at $3, 1$ a $0$ .

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Bước 2.1

Perform the row operation $R_{3} = R_{3} - 2 R_{1}$ to make the entry at $3, 1$ a $0$ .

$[\begin{array}{c} 1 & 4 & 3 & - 2 \\ 0 & 1 & 5 & - 4 \\ 2 - 2 \cdot 1 & 7 - 2 \cdot 4 & 1 - 2 \cdot 3 & - 2 - 2 \cdot - 2 \end{array}]$

Bước 2.2

Rút gọn $R_{3}$ .

$[\begin{array}{c} 1 & 4 & 3 & - 2 \\ 0 & 1 & 5 & - 4 \\ 0 & - 1 & - 5 & 2 \end{array}]$

Bước 3

Perform the row operation $R_{3} = R_{3} + R_{2}$ to make the entry at $3, 2$ a $0$ .

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Bước 3.1

Perform the row operation $R_{3} = R_{3} + R_{2}$ to make the entry at $3, 2$ a $0$ .

$[\begin{array}{c} 1 & 4 & 3 & - 2 \\ 0 & 1 & 5 & - 4 \\ 0 + 0 & - 1 + 1 \cdot 1 & - 5 + 1 \cdot 5 & 2 - 4 \end{array}]$

Bước 3.2

Rút gọn $R_{3}$ .

$[\begin{array}{c} 1 & 4 & 3 & - 2 \\ 0 & 1 & 5 & - 4 \\ 0 & 0 & 0 & - 2 \end{array}]$

Bước 4

Multiply each element of $R_{3}$ by $- \frac{1}{2}$ to make the entry at $3, 4$ a $1$ .

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Bước 4.1

Multiply each element of $R_{3}$ by $- \frac{1}{2}$ to make the entry at $3, 4$ a $1$ .

$[\begin{array}{c} 1 & 4 & 3 & - 2 \\ 0 & 1 & 5 & - 4 \\ - \frac{1}{2} \cdot 0 & - \frac{1}{2} \cdot 0 & - \frac{1}{2} \cdot 0 & - \frac{1}{2} \cdot - 2 \end{array}]$

Bước 4.2

Rút gọn $R_{3}$ .

$[\begin{array}{c} 1 & 4 & 3 & - 2 \\ 0 & 1 & 5 & - 4 \\ 0 & 0 & 0 & 1 \end{array}]$

Bước 5

Perform the row operation $R_{2} = R_{2} + 4 R_{3}$ to make the entry at $2, 4$ a $0$ .

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Bước 5.1

Perform the row operation $R_{2} = R_{2} + 4 R_{3}$ to make the entry at $2, 4$ a $0$ .

$[\begin{array}{c} 1 & 4 & 3 & - 2 \\ 0 + 4 \cdot 0 & 1 + 4 \cdot 0 & 5 + 4 \cdot 0 & - 4 + 4 \cdot 1 \\ 0 & 0 & 0 & 1 \end{array}]$

Bước 5.2

Rút gọn $R_{2}$ .

$[\begin{array}{c} 1 & 4 & 3 & - 2 \\ 0 & 1 & 5 & 0 \\ 0 & 0 & 0 & 1 \end{array}]$

Bước 6

Perform the row operation $R_{1} = R_{1} + 2 R_{3}$ to make the entry at $1, 4$ a $0$ .

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Bước 6.1

Perform the row operation $R_{1} = R_{1} + 2 R_{3}$ to make the entry at $1, 4$ a $0$ .

$[\begin{array}{c} 1 + 2 \cdot 0 & 4 + 2 \cdot 0 & 3 + 2 \cdot 0 & - 2 + 2 \cdot 1 \\ 0 & 1 & 5 & 0 \\ 0 & 0 & 0 & 1 \end{array}]$

Bước 6.2

Rút gọn $R_{1}$ .

$[\begin{array}{c} 1 & 4 & 3 & 0 \\ 0 & 1 & 5 & 0 \\ 0 & 0 & 0 & 1 \end{array}]$

Bước 7

Perform the row operation $R_{1} = R_{1} - 4 R_{2}$ to make the entry at $1, 2$ a $0$ .

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Bước 7.1

Perform the row operation $R_{1} = R_{1} - 4 R_{2}$ to make the entry at $1, 2$ a $0$ .

$[\begin{array}{c} 1 - 4 \cdot 0 & 4 - 4 \cdot 1 & 3 - 4 \cdot 5 & 0 - 4 \cdot 0 \\ 0 & 1 & 5 & 0 \\ 0 & 0 & 0 & 1 \end{array}]$

Bước 7.2

Rút gọn $R_{1}$ .

$[\begin{array}{c} 1 & 0 & - 17 & 0 \\ 0 & 1 & 5 & 0 \\ 0 & 0 & 0 & 1 \end{array}]$