數學問題(中一)我唔係好識做

1.) 7+2e=9e-14-6e
e=21

2.)5y-4(3y-2)=–20
5y-12y+8 = -20
28 = 7y
y = 4

3.)7k-(9k-16)=14-(19-k)
7k-9k+16 = 14-19+k
21 = 3k
k = 7

4.)2〔p-2(p+1)〕-1=8P+25
2 ( p-2p-1) -1=8p+25
2p-4p-2-1 = 8p+25
10p = -28
p = - 14/5

5 )8s+3s-7÷2=6
11s = 19
s = 19/11

6.)3/4y=1-2/1<-----------係唔係1/2
3/4y=1-1/2
3y= 4 - 2
3y = 2
y = 2/3

7.)1/9(h+9)=5/6-1/2(h+7)
6(h+9) = 45 - 27(h+7)
6h + 54 = 45 - 27h - 189
33h= -198
h = -6

1.)7+2e=9e-14-6e
7+2e-2e=9e-14-6e-2e
7+14 =9e-6e-2e+14-14
21 =1e
21/1 =1e/1
e =21

2.)5y-4(3y-2)=–20
5y-4+4(3y-2)=-20+4
8y-2+2 =-16+2
8y/8 =-14/8
y =-7/4=1有3/4

3.)7k-(9k-16)=14-(19-k)
我猜是1/17

4.)2〔p-2(p+1)〕-1=8P+25
2〔p-2(p+1)〕-1+1=8p+25+1
2〔p-2(p+1-1)〕 =8p+26-1
2(2p-2+2) =8p+25+2
2(2p)-27 =8p+27-27
-25(2p+2p) =8p+2p
-25/10 =10p/10
p =-2.5

5 )8s+3s-7÷2=6

6.)3/4y=1-2/1

7.)1/9(h+9)=5/6-1/2(h+7)

2007-09-19 19:44:04 補充：
5 )8s 3s-7÷2=611s = 19s = 19/116.)3/4y=1-2/1不知道是否是1/23/4y=1-1/23y= 4 - 23y = 2y = 2/37.)1/9(h 9)=5/6-1/2(h 7)6(h 9) = 45 - 27(h 7)6h 54 = 45 - 27h - 18933h= -198h = -6 學好數學，才可做科學家！加油！