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Solve the matrix 3 7 1 2 -4 -4 -6 -15 -12 -4 -3 15 16​

1 Answer

5 votes

Answer:

(x, y, z) = (18/7, 5/7, -16/5)

Explanation:

To solve the matrix, we can use the method of matrix row operations to bring it to its row-echelon form or reduced row-echelon form. Here, we'll use the row-echelon form.

Starting matrix:

3 7 1

2 -4 -4

-6 -15 -12

-4 -3 15

16

Divide the first row by 3:

1 7/3 1/3

2 -4 -4

-6 -15 -12

-4 -3 15

16

Multiply the first row by -2 and add it to the second row:

1 7/3 1/3

0 -14/3 -10/3

-6 -15 -12

-4 -3 15

16

Multiply the first row by 6 and add it to the third row:

1 7/3 1/3

0 -14/3 -10/3

0 -7 0

-4 -3 15

16

Multiply the first row by 4 and add it to the fourth row:

1 7/3 1/3

0 -14/3 -10/3

0 -7 0

0 7 0

16

Divide the second row by -14/3 (or multiply by -3/14):

1 7/3 1/3

0 1 5/7

0 -7 0

0 7 0

16

Add 7/3 times the second row to the first row:

1 0 18/7

0 1 5/7

0 -7 0

0 7 0

16

Add 7 times the second row to the third row:

1 0 18/7

0 1 5/7

0 0 0

0 7 0

16

Subtract 7 times the second row from the fourth row:

1 0 18/7

0 1 5/7

0 0 0

0 0 -5

16

Divide the fourth row by -5:

1 0 18/7

0 1 5/7

0 0 0

0 0 1

-16/5

Now, the matrix is in row-echelon form, and you can read the solution:

x = 18/7

y = 5/7

z = -16/5

So, the solution to the matrix is (x, y, z) = (18/7, 5/7, -16/5).

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