問1題數學題~

1.
3x - 2y = 2 ...... (1)
x - y / 2 = - 4 ...... (2)
From (2), x = - 4 + y / 2 ...... (3)
Sub. (3) into (1),
3 ( - 4 + y / 2 ) - 2y = 2
- 12 + 3y / 2 - 2y = 2
3y / 2 - 2y = 14
- y / 2 = 14
- y = 28
y = -28
Sub. y = - 28 into (3),
x = - 4 + ( - 28 ) / 2
x = - 4 -14
x = -18

y-28
x-18
so easy

y=-28
x=-18

(1) 1.3x-2y=2
(2) x-y/2=-4

(2) x-y/2=-4
2x-y=-8
2x=y-8
y=2x+8

(1) 1.3x-2y=2
1.3x-2(2x+8)=2
1.3x-4x-16=2
-2.7x-18=0
2.7x=-18
x=-20/3

so y=2x+8
y=2(-20/3)+8
y=-40/3+24/3
y=-16/3

3x-3y/2=-12

3x-2y=2
-3x-3y/2=-12

-1/2y=14
y=-28
x=-18