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20 votes
20 votes
2x -y +z = 7
2x + 4y - 2z = 0
x-y + 3z = 2

User EvGeniy Ilyin
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2 Answers

16 votes
16 votes
the first one y = 2/3
User Pravin Raj
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17 votes
17 votes

Answer:

x = 3

y = -2

z = -1.

Explanation:

2x -y +z = 7

2x + 4y - 2z = 0

x-y + 3z = 2

Subtracting the second equation from the first:

-5y + 3z = 7 ------------(A)

Multiply the third equation by -2 and adding this to the second equation:

6y -8z = -4 ..................(B)

Multiply A by 8 and B by 3, we get

-40y + 24z = 56

18y - 24z = -12 Adding:

-22y = 44

y = -2

So substituting for y in A:

-5(-2) + 3z = 7

3z = 7-10 = -3

z = -1.

Finally, substituting for y and z in the first equation:

2x -(-2) + (-1) = 7

2x + 2 - 1 = 7

2x = 7 - 1 = 6

x = 3.

User Mohammad Anini
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2.8k points