方程式計法的問題!!!(問題太多, 打唔落!)

This kind of questions can use the following step to solve

Step 1:
move all constant ( items without x) to the right side.
And all items with x stay at the left side.
i.e.: 3/ 5 - (3/5) + 4 - (4) + x / 3 = 10 - (3/5) - (4)
0 + 0 + x / 3 = 5_2/5
x / 3 = 5_2/5
x / 3 = 27/5

i.e.: 3 - (3) + x / 3 + 4 - (4) + 2x / 7 = 4/5 -(3) - (4)
0 + x / 3 + 0 + 2x / 7 = - 31/5
x / 3 + 2x / 7 = - 31/5

Step 2:
如有需要, 通分母
i.e.: x / 3 = 27/5 ----- Since only one item with x, no need to 通分母

i.e.: ( x / 3 ) * (7/7) + ( 2x / 7 ) * (3/3) = - 31/5
x*(7) / 3*(7) + 2x*(3) / 7*(3) = - 31/5
7x / 21 + 6x / 21 = - 31/5
通分母後, 同分母 ---> 分子可以相加
i.e.: (7x + 6x) / 21 = - 31/5
13x / 21 = - 31/5

Step 3:
兩邊同時乘以帶"x"項的分母, 使帶"x"的項不是分數
i.e. ( x / 3 ) * 3 = ( 27/5 ) * 3
x = 81/5

i.e.: ( 13x / 21 ) * 21 = (- 31/5 ) * 21
13x = - 651/5

Step 4:
如有需要, 兩邊同時除以"與 x 相乘的數字", 以使 x 獨立.
i.e.: 13x / (13) = (- 651/5 ) / (13)
x = - 651/65


Hope these steps can help you finish other questions.

Step 1:
move all constant ( items without x) to the right side.
And all items with x stay at the left side.
(又名: 左邊有 x , 右邊冇 x )
Step 2:
如有需要, 通分母
通分母後, 同分母 ---> 分子可以相加
(又名: 通分母)
Step 3:
兩邊同時乘以帶"x"項的分母,
使帶"x"的項不是分數.
(又名: 乘分母)
Step 4:
如有需要, 兩邊同時除以"與 x 相乘的數字",
使 x 獨立.
(又名: 除 x 隻數)

2006-12-08 15:25:07 補充：
Please Pay Attention!!!From 作狀大師 and benrain234 's answer:x/3 2x/7=4/5-3-4 7x 6 3x/21=-31/5 IS NOT CORRECT!!!!x/3 2x/7 is NOT equal to 7x 6 3x/21x/3 2x/7 is equal to (7*1 x 2*3 x) / 21 = (7x 6x) / 21 = 13x / 21

2006-12-08 15:34:19 補充：
Sorry, missing some " " in the Attention.Please Pay Attention!!!From 作狀大師 and benrain234 的 answer:x/3 2x/7=4/5-3-4 7x 6 3x/21=-31/5 IS NOT CORRECT!!!!x/3 2x/7 is NOT equal to 7x 6 3x/21x/3 2x/7 is equal to (7*1 x 2*3 x) / 21 = (7x 6x) / 21 = 13x / 21

3/ 5 + 4+x / 3 = 10
3/5+4+x=30
3/5+4=30-x
3/5=26-x
3=130-5x
5x=127
x=25.4

3+x /3 + 4+2x / 7 = 4/5
3+x/3+4+2x=4/5*7
3+x/3+4=5 3/7-2x
3+x/3=1 3/7-2x
3+x=2 2/7-6x
3=2 2/7-7x
7x=-5/7

2006-12-08 13:33:04 補充：
oh no1.3/5+4+x/3=103/5+4+x/3-3/5=10-3/5 4+x/3-4=47/5-20/5 x/3=27/5x/3*3=27/5*3 2.3+x/3+4+2x/7=4/5x/3+2x/7=4/5-3-4 7x+6+3x/21=-31/5 10x+6/21=-31/5 10x/21+6/21-6/21=-31/5-6/21 10x/21=-961-30/21 10x/21*21=-991/21*21 10x=-991

3/5 + 4 + x/3 = 10
3/5+x/3 = 10 -4...........................先把整數放在右方
x/3 = 6-3/5...........................再把另一些份數放在右方
x/3= (30-3)/5.......................通份母後
x = (30-3)/5 * 3..................求得 x 值
=27/5 * 3


3 + x/3 + 4 + 2x/7 = 4/5
x/3 + 2x/7 = 4/5 - 4 - 3
(7x + 6x)/ 21 = 4/5 -7
(13x)/21 = (4-35) / 5
13x = -31/5 * 21
x = (-31/5 * 21)/13

1.3/5+4+x/3=10
3/5+4+x/3-3/5=10-3/5 先減3/5
4+x/3-4=47/5-20/5 再減4,把多餘的整數全抽去
x/3=27/5 只餘下x/3and27/5互相對峙
x/3*3=27/5*3

2.3+x/3+4+2x/7=4/5
x/3+2x/7=4/5-3-4 把x集中到left side
7x+6+3x/21=-31/5 通分母
10x+6/21=-31/5 通分母完成
10x/21+6/21-6/21=-31/5-6/21 將兩邊-6/21
10x/21=-961-30/21 通分母has finished
10x/21*21=-991/21*21 將兩邊*21
10x=-991 最後將兩邊/10就完成了