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Obtain an equivalent system by performing the stated elementary operation on the

ID: 3038183 • Letter: O

Question

Obtain an equivalent system by performing the stated elementary operation on the system. Replace the fourth equation by the sum of itself and 3 times the second equation x - 2y + 5z - 6w = 4 4y - z - 4w = -5 3y - 4z + 2w = -3 5y - 5z - 2w = 8 x - 2y + 5z - 6w = 4 12y - 3z - 12w = -15 3y - 4z + 2w = -3 5y - 5z - 2w = 8 x - 2y + 5z - 6w = 4 4y - z - 4w = -5 3y - 4z + 2w = -3 17y - 8z - 14w = -7 x - 2y + 5z - 6w = 4 4y - z - 4w = -5 3y - 4z + 2w = -3 12y + 3z - 14w = -7 x - 2y + 5z - 6w = 4 4y - z - 4w = -5 3y - 4z + 2w = -3 -7y + 8z + 10w = 23

Explanation / Answer

x - 2y + 5z - 6w = 4                    (1)

     4y - z - 4w = -5                     (2)

    3y  - 4z + 2w = -3                    (3)

    5y - 5z - 2w = 8                    (4)

we need to replace equation-4 by equation-4 + 3 times equation-2.

3 times of equation-2 is

3 * (4y - z - 4w = -5)

12y - 3z -12w = -15        // multiply each term by 3.

now add it with eq-4

12y - 3z -12w = -15

5y - 5z - 2w = 8             adding we get

17y - 8z - 14w = -7