✔ 最佳答案
1)
3x - 2y = 13
5x + 6y = 3
3(3x - 2y) = 3(13)
9x - 6y = 39
...9x - 6y = 39
+) 5x + 6y = 3 (addition)
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14x = 42
14x = 42
x = 42/14
x = 3
3x - 2y = 13
3(3) - 2y = 13
9 - 2y = 13
2y = 9 - 13
2y = -4
y = -4/2
y = -2
∴ x = 3 , y = -2
= = = = = = = =
2)
p = 31 + q
5p = -3q + 211
p = 31 + q
5(p) = 5(31 + q)
5p = 155 + 5q
5p = 5q + 155
...5p = 5q + 155
–) 5p = -3q + 211 (subtraction)
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0 = 8q - 56
0 = 8q - 56
8q = 56
q = 56/8
q = 7
p = 31 + q
p = 31 + 7
p = 38
∴ p = 38 , q = 7