Răspuns:
Explicație pas cu pas:
a)
2(x + y +1) - 3(2x - y - 3) = 12
4(2x - y - 1) + 3(3 -x - y) = 3
--------
2x + 2y + 2 - 6x + 3y + 9 = 12
8x - 4y - 4 + 9 - 3x - 3y = 3
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-4x + 5y = 12 - 9 - 2
5x - 7y = 3 + 4 - 9
--------
-4x + 5y = 1
5x - 7y = -2
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y = (1 + 4x)/5
5x - 7(1 + 4x)/5 = -2
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25x - 7(1 + 4x) = -10
25x - 7 - 28x = -10
-3x = -10 + 7 = -3
x = -3/-3 = 1
y = (1 + 4)/5 = 5/5 = 1