中一方程數`1定要入尼答,20點~~~~~~~~~~~~~~

第1條`
2[a - (1 - a)] = 3(a - 1) + 8
2[a - 1 + a] = 3a - 3 + 8
2[1] = 3a + 5
3a + 5 = 2
3a = 2 - 5
3a = -3
a = -1


第2條`
3b - b/3 = 16
3 x (3b - b/3) = 3 x 16
9b - b = 48
8b = 48
b = 6


第3條`
2x = 3(1 - x) - (x + 1)
2x = 3 - 3x - x - 1
2x = 2 - 4x
2x + 4x = 2
6x = 2
3x = 1
x = 1/3


第4條`
3(x - 0.5) - 2(x - 4.5) = 7
3x - 1.5 - 2x + 9 = 7
x + 7.5 = 7
x = 7 - 7.5
x = -0.5


第5條`
(x - 1)/2 = (x + 1)/3 + 1
6[(x - 1)/2] = 6[(x + 1)/3 + 1]
3(x - 1) = 2(x + 1) + 6
3x - 3 = 2x + 2 + 6
3x - 3 = 2x + 8
3x - 2x = 8 + 3
x = 11


第6條`
7u - (4u - 1)/2 = 21
2[7u - (4u - 1)/2] = 2 x 21
14u - (4u - 1) = 42
14u - 4u + 1 = 42
10u + 1 = 42
10u = 42 - 1
10u = 41
u = 41/10
u = 4.1


第7條`
9(2a - 1) = 3[4(1 + 2a) -5] - 8a
18a - 9 = 3[4 + 8a - 5] - 8a
18a - 9 = 3[8a - 1] - 8a
18a - 9 = 24a - 3 - 8a
18a - 9 = 16a - 3
18a - 16a = -3 + 9
2a = 6
a = 6/2
a = 3


第8條`
(1/3)(t + 9) = (1/3) - 0.5(t + 3)
6[(1/3)(t + 9)] = 6[(1/3) - 0.5(t + 3)]
2(t + 9) = 2 - 3(t + 3)
2t + 18 = 2 - 3t - 9
2t + 18 = -3t - 7
2t + 3t = -7 - 18
5t = -25
t = -5


第9條`
(2 - t)/4 - t = (2t - 3)/5
20[(2 - t)/4 - t] = 20[(2t - 3)/5]
5(2 - t) - 20t = 4(2t - 3)
10 - 5t - 20t = 8t - 12
10 - 25t = 8t -12
-25t - 8t = -12 - 10
-33t = -22
3t = 2
t = 2/3


第10條`
(2n - 5)/3 = (n - 10)/9
9[(2n - 5)/3] = 9[(n - 10)/9]
3(2n - 5) = n - 10
6n - 15 = n - 10
6n - n = -10 + 15
5n = 5
n = 5/5
n = 1

1. 2[a-(1-a)]=3(a-1)+8
2[a-1+a]=3a-3+8
4a-2=3a+5
4a-3a=7
a=7

2. 3b-b/3=16
-b/3=16-3b
-b=48-9b
8b=48
b=6

(3b-b)/3=16
2b=48
b=24

唔知你打哪個...你e條睇番答案....實有一個岩

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

4. 3(x-0.5)-2(x-4.5)=7
3x-1.5-2x+9=7
x+7.5=7
x=-0.5

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

6. 7u-(4u-1)/2=21
-4u+1/2=21-7u
-4u+1=42-14u
10u=42-1
u=4.1

7. 9(2a-1)=3[4(1+2a)-5]-8a
18a-9=3[4+8a-5]-8a
18a-9=12+24a-15-8a
18a-9=16a-3
2a=6
a=3

8. (1/3)*(t+9)=(1/3)-0.5(t+3)
(t+9)/3=1/3-0.5t-1.5
t+9=3(1/3-0.5t-1.5)
t+9=1-1.5t-4.5
2.5t=-12.5
t=-5

10. (2n-5)/3=(n-10)/9
9(2n-5)=3(n-10)
18n-45=3n-30
15n=15
n=1

諗左好耐....第9題到係唔識

2009-08-06 17:11:22 補充：
無奈...第5,9題...我理解能力太廢

5. (x-1)/2=(x+1)/3+1

以為是(x-1)/2=[(x+1)/3+1] 諗住個1 係跟3一樣是分母

9. (2 - t)/4 - t = (2t - 3)/5

一樣以為是[(2 - t)/4 - t] = (2t - 3)/5 諗住個-t係跟4一樣是分母