二元一次方程

3X+7Y÷2=12-----1
5Y-2X÷3=32-----2
6x+7y=24---3
15y-2x=96---4
x=(24-7y)/6
putx=(24-7y)/6 into 4
15y-2(24-7y)/6=96
45y-24+7y=288
y=6
x=(24-42)/6
x=-3

X÷3+Y÷2=2--1
Y÷6-X÷4=- 8---2
2x+3y=12---3
2y-3x=-96---4
x=(12-3y)/2
2y-3(12-3y)/2=-96
4y-36+9y=-192
y=-12
x=(12-3y)/2
x=24

1. 3X+7Y÷2=12... (1)
5Y-2X÷3=32... (2)

(1)x2: 6X + 7Y = 24... (3)
(2)x9: 45Y - 6X = 288.. (4)

(3) + (4):
6X + 7Y + 45Y - 6X = 24 + 288
52Y= 312
Y= 6 (ans)
以Y=6代入(3):
6X + 7x6 = 24
6X= 24 - 42 = 18
X = 3 (ans)

2. X/3 + Y/2 = 2... (1)
Y/6 - X/4 = 8... (2)

(1)x18: 6X + 9Y = 36 ... (3)
(2)x12: 4Y - 6X = -192.. (4)

(3) + (4):
6X + 9Y + 4Y - 6X = 36 - 192
13Y = - 156
Y = -12 (ans)
以Y=-12代入(4):
-12x4 - 6X = -192
- 6X = -192 + 48 = -144
X = 24 (ans)

1. 3X+7Y÷2=12 . . . . (1)
5Y-2X÷3=32 . . . . . . (2)
(1) x 2 : 6X+7Y=24 . . . . . (3)
(2) x 3 : 15Y-2X=96
45Y-6X=288 . . . . . . . . . . . . (4)
(3)+(4) : 52Y=312
Y=6
代入(1) : 3X+21=12
X=-3

2. X÷3+Y÷2=2 . . . . . (1)
Y÷6-X÷4=- 8 . . . . . . (2)
(1) x 6 : 2X+3Y=12 . . . . . (3)
(2) x 12 : 2Y-3X=- 96 . . . (4)
(3) x 2 : 4X+6Y=24 . . . . . . . . . (5)
(4) x 3 : 6Y-9X=- 288 . . . . . . . . (6)
(5)-(6): 13X=312
X=24
Y=-12