✨ 最佳解答 ✨
(以下照我寫的打,可能有打錯的地方)
6.
2(x + y) + 3(y - x) = 30
9x + 2(x + y) = 126
-x + 5y = 30
11x + 2y = 126
-2x + 10y = 60
55x + 10y = 630
57x = 570, => x = 10, y = 8
7.
3x - 4y - 1 = 6x - 3y + 6
8x + 4y + 6 = 7x + y + 9
3x + y = -7
x + 3y = 3
3x + y = -7
3x + 9y = 9
8y = 16, => y = 2, x = -3
8.
3x + 2y = 6 + 6x
2x + 3y = 6 + 6y
3x - 2y = -6
2x - 3y = 6
6x - 4y = -12
6x - 9y = 18
5y = -30, => y = -6, x = -6
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