maths ................

1.

8x-3=4x-5

8x - 3 + 3 - 4x = 4x - 5 + 3 - 4x

4x = -2

4x ÷ 4 = -2 ÷ 4

x = -0.5

2.

7(1.2-k)=14k

8.4 - 7k = 14k

8.4 - 7k + 7k = 14k + 7k

8.4 = 21k

21k = 8.4

21k ÷ 21 = 8.4 ÷ 21

k = 0.4

3.

-6(3-2n)=5(n-2)

-18 + 12n = 5n - 10

-18 + 12n + 18 - 5n = 5n - 10 + 18 - 5n

7n = 8

7n ÷ 7 = 8 ÷ 7

n = 1 + 1 ÷ 7

4.

4(3(y-2)+1)=-14

12 ( y - 2 ) + 4 = -14

12y - 24 + 4 = -14

12y - 20 = -14

12y - 20 + 20 = -14 + 20

12y = 6

12y ÷ 12 = 6 ÷ 12

y = 0.5

5.

2(a-(1-a))=3(a-1)+8

2 ( a - 1 + a ) = 3a - 3 + 8

2 ( 2a - 1 ) = 3a + 5

4a - 2 = 3a + 5

4a - 2 + 2 - 3a = 3a + 5 + 2 - 3a

a = 7

2010-10-23 15:58:15 補充：
001 ,

see No.3 ,

is 8 / 7 , not 7 / 8

1.8x-3=4x-5
8x-4x=-5+3
4x=-2
x=-0.5
2.7(1.2-k)=14k
1.2-k=2k
1.2=3k
k=0.4
3.-6(3-2n)=5(n-2)
-18+12n=5n-10
12n-5n=18-10
7n=8
n=8/7
4.4(3(y-2)+1)=-14
3(y-2)+1=-56
3(y-2)=-57
y-2=-19
y=-17
5.2(a-(1-a))=3(a-1)+8
2a-2(1-a)=3a-3+8
-2+2a=a+5
2a-a=5+2
a=7

1.8x-3=4x-5 4x=-5+3 4x=-2 x=-0.52. 7(1.2-k)=14k
8.4-7k=14k 8.4=21k k=0.4 3.-6(3-2n)=5(n-2) -18+12n=5n-10

7n=8n=8/7
4.4(3(y-2)+1)=-14(3(y-2)+1)=-14/43y-6+1=-3.53y-5=-3.53y=1.5y=0.5
5.2(a-(1-a))=3(a-1)+82a-2(1-a)=3a-3+8-2+2a=52a=7a=3..5

1) 8x-3=4x-5
4x=-2
x=-1/2
2) 7(1.2-k)=14k
8.4-7k=14k
7k=8.4
k=1.2
3) -6(3-2n)=5(n-2)
-18+12n=5n-10
7n=8
n=7/8
4) 4(3(y-2)+1)=-14
4(3y-6+1)=-14
4(3y-5)=-14
12y-20=-14
12y=6
y=1/2
5)2(a-(1-a))=2(a-1)+8
2(a-1+a)=2a-2+8
2(2a-1)=2a+6
4a-2=2a+6
2a=8
a=4