Help me!( From 1 Maths)

1) 5(x-7)=3x+8
5x-35=3x+8
2x=43
x=43/5

2) 9-3(8-x)=-3x+9
9-24+3x=-3x+9
6x=24
x=4

3) r/7+2/7=3
r+2=21
r=19

4) 2x/5-4/5=2
2x-4=10
2x=14
x=7

5) x/2-1/4=3/4
2x-1=3
2x=4
x=2

6) x/3+1/6=2
2x+1=12
2x=11
x=11/2

7) y+1/2=4/3
6y+3=8
6y=5
y=5/6

8) 2x-1/3=x+2/4
24x-4=12x+6
12x=10
x=5/6

9) x-3/2=10-2x
2x-3=20-4x
6x=23
x=23/6

10) 2x-7/3=6-x
6x-7=18-3x
9x=25
x=25/9

11) 2x+4/5-4x=8
10x+4-20x=8
-10x=4
x=-2/5

12) x/4+1=x-4/2
x+4=4x-8
3x=12
x=4

13) 例如2/5+4/9,最簡單的方法係把2/5 x 9/9,4/9 x 5/5,由於9/9和5/5係等於1,所以係對數值沒有影響的.之後便會得出18/45 + 20/45,這時候便能以普通的方數加減運算.便等於38/45.

2006-12-03 20:06:38 補充：
第一題打錯字1) 5(x-7)=3x+85x-35=3x+82x=43x=43/2

1) 5(x-7)=3x+8 (需過程)
5x-35 = 3x+8
2x = 43
x = 21.5

2) 9-3(8-x)=-3x+9 (需過程)
9-24+3x = 9-3x
3x - 33 = 9-3x
6x = 42
x = 7

3) r/7+2/7=3 (需過程)
r+2 = 21
r = 19

4) 2x/5-4/5=2(需過程)
2x-4 = 10
2x = 14
x = 7

5) x/2-1/4=3/4(需過程)
2x-1 = 3
2x = 4
x = 2

6) x/3+1/6=2(需過程)
2x+1 = 12
2x = 11
x = 5.5

7) y+1/2=4/3(需過程)
3(y+1) = 8
3y+3 = 8
3y = 5
y = 5/3

8) 2x-1/3=x+2/4(需過程)
4(2x-1) = 3(x+2)
8x-4 = 3x+6
5x = 10
x = 2

9) x-3/2=10-2x(需過程)
x-3 = 20-4x
5x = 23
x = 4.6

10) 2x-7/3=6-x(需過程)
2x-7 = 18-3x
5x = 25
x = 5

11)2x+4/5-4x=8(需過程)
2x+4-20x = 40
-18x = 36
x = -2

12)x/4+1=x-4/2(需過程)
x+4 = 2x-8
-x = -12
x = 12

13)我想分數點通分?(給例子)
a/b + c/d
全式乘(b,d的LCM)
= (ad+cb)/bd

1) 5(x-7)=3x+8 (需過程)

5x - 35 = 3x + 8

2x = 43

x = 21.5 #
---------------------------------------------------------------------------------------------------

2) 9-3(8-x)=-3x+9 (需過程)

-24 + 3x = -3x

6x = 24

x = 4 #
------------------------------------------------------------------------------------------------------------------

3) r/7+2/7=3 (需過程)

r + 2 = 21

r = 19 #
----------------------------------------------------------------------------------------------------------

4) 2x/5-4/5=2(需過程)

2x - 4 = 10

2x = 14

x = 7 #
------------------------------------------------------------------------------------------------------------

5) x/2-1/4=3/4(需過程)

2x - 1 = 3

2x = 4

x = 2 #
------------------------------------------------------------------------------------------------------------

6) x/3+1/6=2(需過程)

2x + 1 = 12

2x = 11

x = 5.5 #
------------------------------------------------------------------------------------------------------

7) y+1/2=4/3(需過程)

y + 3 = 8

y = 5 #
-------------------------------------------------------------------------------------------------------

8) 2x-1/3=x+2/4(需過程)

x = 6 + 4

x = 10 #
-------------------------------------------------------------------------------------------------------

9) x-3/2=10-2x(需過程)

x - 3 = 20 - 4x

5x = 23

x = 4.6 #
-------------------------------------------------------------------------------------------------------

10) 2x-7/3=6-x(需過程)

2x - 7 = 18 - 3x

5x = 25

x = 5 #
-------------------------------------------------------------------------------------------------------

11)2x+4/5-4x=8(需過程)

-2x = 8 - 4/5

-2x = 36

x = -18 #
-------------------------------------------------------------------------------------------------------

12)x/4+1=x-4/2(需過程)

x + 4 = 4x - 8

3x = 12

x = 4 #
------------------------------------------------------------------------------------------------------

13)我想(知)分數點通分?(給例子)
1 3
------- + -------
2 4

1x 2 3
= --------- + -------
2x 2 4

2 3
= ------ + ------
4 4

5
= ------
4 #

1) 5(x-7)=3x+8 (需過程)
5x-35 = 3x+8
2x = 43
x = 21.5

2) 9-3(8-x)=-3x+9 (需過程)
9-24+3x = 9-3x
3x - 33 = 9-3x
6x = 42
x = 7

3) r/7+2/7=3 (需過程)
r+2 = 21
r = 19

4) 2x/5-4/5=2(需過程)
2x-4 = 10
2x = 14
x = 7

5) x/2-1/4=3/4(需過程)
2x-1 = 3
2x = 4
x = 2

6) x/3+1/6=2(需過程)
2x+1 = 12
2x = 11
x = 5.5

7) y+1/2=4/3(需過程)
3(y+1) = 8
3y+3 = 8
3y = 5
y = 5/3

8) 2x-1/3=x+2/4(需過程)
4(2x-1) = 3(x+2)
8x-4 = 3x+6
5x = 10
x = 2

9) x-3/2=10-2x(需過程)
x-3 = 20-4x
5x = 23
x = 4.6

10) 2x-7/3=6-x(需過程)
2x-7 = 18-3x
5x = 25
x = 5

11)2x+4/5-4x=8(需過程)
2x+4-20x = 40
-18x = 36
x = -2

12)x/4+1=x-4/2(需過程)
x+4 = 2x-8
-x = -12
x = 12

13)我想分數點通分?(給例子)
a/b + c/d
全式乘(b,d的LCM)
= (ad+cb)/bd

1) 5(x-7)=3x+8
5x-35=3x+8
5x-3x=8+35
2x=43
x=43/2
=21.5

2) 9-3(8-x)=-3x+9
9-24+3x=-3x+9
3x+3x=9-9+24
6x=24
x=4