方程式的問題?

In solving this kind of problems, we must first expand everything in the brackets, and then add up similar terms. Then put the unknown term on one side and constant term on the other. Finally you divide the coefficient of the unknown term and get the answer.

Question 1:
8w - 5 - 2w = 0
6w = 5
w = 5/6

Question 2:
0 = f + 80 + 6f + 4
7f = -84
f = -12

Question 3:
0.3k + 0.2k + 5 = -15
0.5k = -20
k = -40

Question 4:
15 = 5(2a - 3)
15 = 10a - 15
30 = 10a
a = 3

Question 5:
6-3(4+7b) = 36
6 - 12 - 21b = 36
-6 - 21b = 36
-21b = 42
b = -2

Question 6:
1.3x - 7 = 2.5x - 1
-6 = 1.2x
x = -5

Question 7:
4n - 11 - 8n = 22 - n
-4n - 11 = 22 - n
-33 = 3n
n = -11

Question 8:
8(y - 0.3) = 1 + 2(0.3y + 2)
8y - 2.4 = 1 + 0.6y + 4
7.4y = 1 + 4 + 2.4
7.4y = 7.4
y = 1

Question 9:
h-[2(h-1) + 10] = 5(h-34)
h-[2h - 2 + 10] = 5h - 170
h - 2h + 2 - 10 = 5h - 170
-h - 8 = 5h - 170
-6h = -162
h = 27

2006-10-17 20:41:40 補充：
All answers are double checked.

1. 8w-5-2w=0
8w-2w=0+5
6w=5
w=5/6
w=0.83333333333333333333333333333333333333333...
w～0.83(一位有效數字)

2. 0=f+80+6f+4
f+80+6f+4=0
2f=0-80-4
2f=-84
f=-84/2
f=-42

3. 0.3k+0.2k+5= -15
0.5k=-15-5
0.5k=-20
k=-20/0.5
k=-40

4. 15=5(2a-3)
5(2a-3)=15
10a-15=15
10a=15+15
10a=30
a=30/10
a=3

5. 6-3(4+7b)=36
6-12-21b=36
-21b=36+6+12
-21b=54
b=54/-21
b=-2.571428571...
b～-2.571(四位有效數字)

6. 1.3x-7=2.5x-1
-7+1=2.5x-1.3x
-6=1.2x
x=-6/1.2
x=-5

7. 4n-11-8n=22-n
-11-22=-n+4n+8n
11n=-33
n=-33/11
n=-3

8. 8(y-0.3)=1+2(0.3y+2)
8y-2.4=1+0.6y+4
8y-0.6y=4+2.4
7.4y=6.4
y=6.4/7.4
y=0.86486486486486486...
y～0.865(三位有效數字)

9. h-[2(h-1)+10]=5(h-34)
h-[2h-2+10]=5h-170
h-2h+2-10=5h-170
2-10+170=5h-h+2h
6h=162
h=162/6
h=27

在這裡，～的意思是大約等於

1. w=5/6
2. f=-12
3. k=-40
4. a=3
5. b=-2
6. x=-5
7. n=-11
8. y=1
9. h=27

8w-5-2w=0
6w=5
w=5分之6

0=f+80+6f+4
0=7f+84
-84=7f
f=-12

2006-10-17 19:29:49 補充：
so easy,do it my yourself!