有d數學題唔明!!! 快急問.......... (15分)

1.) 6 - 2(x - 3)= x - 3
6-2x+6=x-3
15=3x
x=5

2.) 4x - 2( 1 + 3x) = 5 - 3(x +2)
4x-2-6x=5-3x-6
x=1

3.) 3 - 2(x - 2) = 8
3-2x+4=8
-1=2x
x=-1/2

1. 6 - 2(x - 3) = x - 3
__6 - 2x + 6 = x - 3 (左邊展開括號)
____15 - 2x = x (左右同時加以 3)
________15 = 3x (左右同時加以 2x)
_________5 = x (左右同時除以 3)
_________x = 5 (左右互換位置)

2. 4x - 2(1 + 3x) = 5 - 3(x + 2)
____4x - 2 - 6x = 5 - 3x - 6 (左邊和右邊展開括號)
_______- 2x - 2 = - 3x - 1 (左右各自重組)
___________x = 1 (左右同時加以 (3x + 2))

3. 3 - 2(x - 2) = 8
__3 - 2x + 4 = 8 (左邊展開括號)
_______- 2x = 1 (左右同時減以 7)
_________x = - 1/2 (右同時除以 - 2)