The system:
- 4 x + 4 y + 5 z = 9
- 2 x + 2 y + z = 3
- 4 x + 5 y = 4
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Let`s take the 1st and the 2nd equation:
- 4 x + 4 y + 5 z = 8
- 2 x + 2 y + z = 3 / * ( - 2 ) / multiply both sides of equation by - 2 . /
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- 4 x + 4 y + 5 z = 9
+
4 x - 4 y - 2 z = - 6
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3 z = 3 = > z = 1
Then the 2nd and the 3rd equation:
- 2 x + 2 y = 3 - 1 / * ( - 2 )
- 4 x + 5 y = 4
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4 x - 4 y = - 4
+
- 4 x + 5 y = 4
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y = 0
- 4 x + 5 * 0 = 4
- 4 x = 4
x = - 1
Answer: x = - 1, y = 0, z = 1.
