中一的數學題

12)

S/5 + 2 = -1
S/5 = -1 -2 = -3
S = (-3) X 5
S= -15

15)

E/9 - 1/9 = 1
E/9 = 1 + 1/9 = 10/9
E = 10/9 X 9
E=10

18)

5D/2 + 6 = -4
5D/2 = -4 -6 = -10
5D = -10 x 2 = 20
D = 20/5 = 4

21)

2/3 - X/2 = 1/6
- X/2 = 1/6 - 2/3 = 1/6 - 4/6 = - 3/6
X/2 = 3/6
X = 3/6 X 2
X = 1

24)

3R/5 + 8 + 4/5 = -1/2
3R/5 = -1/2 - 8 - 4/5 = 93/10
3R = 93/10 X 5 =
R = 93/2 /3 = 15 1/2

2006-11-23 18:14:20 補充：
18) 5D/2 + 6 = -45D/2 = -4 -65D = -10 X 2 = -20d = -20 / 5 = -4

12) 5份之s+2=-1
答:s=(-1-2)乘5
= -15

15) 9份之e-9份之1=1
答: 9份之e-1=1
e-1=9
e=10

18) -4=2份之5d+6
答: -8=5d+6
-14=5d
d=負5份之14/ -2.8

21) 3份之2-2份之x=6份之1
答:6份之4-3x=6份之1
4-3ｘ＝１
　　　　－３ｘ＝－３
　　　　　　ｘ＝１

24) 5份之3r+8+5份之4=-2份之1
答：5份之3r+8=-1又１０份之３
　　　　3r+8＝－６又２份之１－８
　　　　　３ｒ＝－１４又２份之１
　　　　　　ｒ＝－４又６份之５

12) 5份之s+2= -1
5份之s= -1-2
5份之s= -3
s= -3*5
s=-15
15) 9份之e-9份之1=1
9份之e-1=1
e-1= 1*9
e-1=9
e=9+1
e=10
18) 2份之5d+6= -4
5d+6= -4*2
5d+6 = -8
5d= -8-6
5d= -14
d= 5份之-14

12)5份之s+2=-1

5份之s=-1-2
s =-3x5
s=-15