help!功課好難啊!(10點)

Question

solve the following equations.
3(x-0.5)-2(x-4.5)=7

6﹝２（２－ｙ）－３ｙ﹞＝２４

９（２ａ－１）＝３﹝4(1+2a)-5﹞-8a

1/3(t+9)=1/3-0.5(t+3)

Answer 1

3(x-0.5)-2(x-4.5)=7
3x - 1.5 - 2x + 9 = 7
x + 7.5 = 7
x = -0.5

6﹝２（２－ｙ）－３ｙ﹞＝２４
6 (4 - 2y - 3y) = 24
24 - 30y = 24
30y = 0
y = 0

９（２ａ－１）＝３﹝4(1+2a)-5﹞-8a
18a - 9 = 3 ( 4 + 8a - 5) - 8a
18a - 9 = 24a - 3 - 8a
18a - 9 = 16a - 3
2a = 6
a = 3

1/3(t+9)=1/3-0.5(t+3 )
t + 9 = 1 - 1.5t - 4.5
2.5t = 1 - 4.5-9
2.5t = -12.5
t = -5

Answer 2

3(x-0.5)-2(x-4.5)=7
3x-1.5-2x+9=7
3x-2x-1.5+9=7
x+7.5=7
x=-0.5


6(2(2-y)－3y)＝24
6(4-2y-3y)=24
24-12y-18y=24
-6y=0
y=0

9(2a-1)=3(4(1+2a)-5)-8a
18a-9=3(2a-1)-8a
18a-9=6a-3-8a
18a-6a+8a=-3+9
20a=6
a=3/10

1/3(t+9)=1/3-0.5(t+3)
3(1/3(t+9))=3(1/3-0.5(t-3))
t+9=1-1.5(t-3)
t+9=1-1.5t-4.5
1.5t+t=1-4.5+9
2.5t=5.5
10(2.5t)=(5.5)10
25t=55
t=5/11

2006-10-26 21:24:25 補充：
9(2A-1)=3(4(1+2A)-5)-8A18A-9=3(4+8A-5)-8A26A=12+24A-15+92A=6A=31/3(t+9)=1/3-0.5(t+3) T+9=1-1.5T-4.52.5T=-12.5T=-5

Answer 3

1)3(x-0.5)-2(x-4.5)=7

3x-1.5-2x+9=7

x=7-7.5

x=-0.5

2)6(2(2-y)-3y)=24

6(4-2y-3y)=24

4-5y=4

y=0

3)9(2a-1)=3(4(1+2a)-5)-8a

18a-9=3(4+8a-5)-8a

26a=12+24a-15+9

2a=6

a=3

4)1/3(t+9)=1/3-0.5(t+3)

t+9=1-1.5t-4.5

2.5t=-12.5

t=-5

Answer 4

3(x-0.5)-2(x-4.5)=7
3X-1.5-2X+9=7
X=7-7.5
X=-0.5

6(2(2-Y)-3Y)=24
6(4-2Y-3Y)=24
4-5Y=4
Y=0

9(2A-1)=3(4(1+2A)-5)-8A
18A-9=3(4+8A-5)-8A
26A=12+24A-15+9
2A=6
A=3

1/3(t+9)=1/3-0.5(t+3)
T+9=1-1.5T+4.5
2.5T=-3.5
T=1.4

2006-10-26 21:04:04 補充：
1/3(t+9)=1/3-0.5(t+3) T+9=1-1.5T-4.52.5T=-12.5T=-5搞錯左正負添,,SOR-3-