中一題目 請解答 (有步驟)

1)24+2x=5x+9
3x=15
x=5


2)2(5－k)+3(2k+9)=25
10-2k+6k+27=25
4k+37=25
4k= -12
k= -3


3)4x/7－x/3=5
3(4x)-7x=21(5)
12x-7x=105
5x=105
x=21


4)1/4(x+17)=1/6(43－x)
4(x+17)=6(43-x)
4x+68=258-6x
10x=190
x=19

2006-11-20 21:47:38 補充：
4) (x 17)/4=(43-x)/63(x 17)=2(43-x)3x 51=86-2x5x=35x=7

Q1
24+2x=5x+9
2x-5x=9-24
-3x=-15
x=5

Q2
2(5-k)+3(2k+9)=25
10-2k+6k+27=25
4k=25-10-27
4k=-12
k=-3

Q3
4x/7-x/3=5
12x-7x=105
5x=105
x=21

Q4
1/4(x+17)=1/6(43-x)
3(x+17)=2(43-x)
Both sides X12
3x+51=86-2x
3x+2x=86-51
5x=35
x=7

1) 24 + 2x = 5x + 9
24 = 3x + 9
15 = 3x
Therefore x = 5

2) 2(5 - k) + 3 (2k + 9) = 25
(10 - 2k) + (6k + 27) = 25
4k + 37 = 25
4k = -12
Therefore k = -3

3) 4x/7 - x/3 = 5
(4x * 3)/(7 * 3) - (x * 7)/(3 * 7) = 5
(12x / 21) - (7x / 21) = 5
(12x - 7x) / 21 = 5
5x / 21 = 5
5x = 105
Therefore x = 21

4) 1/4 (x + 17) = 1/6 (43 - x)
(x + 17) = 4/6 (43 - x)
(x + 17) = 2/3 (43 - x)
(x + 17) = (86/3) - 2/3 (x)
(x + 17) = 1/3 (86 - 2x)
3 (x + 17) = 86 - 2x
3x + 51 = 86 - 2x
3x + 2x + 51 = 86
5x + 51 = 86
5x = 35
Therefore x = 7

1) 24 + 2x = 5x + 9
24 - 9 = 5x - 2x
15 = 3x
x = 5

2) 2(5 - k) + 3(2k + 9) = 25
10 - 2k + 6k + 27 = 25
-2k + 6k = 25-27-10
4k = -12
k = 3

3) 4x/7 - x/3 = 5
12x/21 - 7x/21 = 5
5x/21 = 5
x = 5*21/5
x = 21


4) 1/4(x + 17) = 1/6(43 - x)
24[1/4(x+17)]=24[1/6(43-x)]
6(x + 17) = 4(43 - x)
6x +102 = 172 - 4x
6x + 4x = 172 - 102
10x = 70
x = 10

1)24+2x=5x+9
24 - 9 = 5x - 2x
15 = 3x
x = 15 / 3
x = 5

2)2(5－k)+3(2k+9)=25
10 -2k + 6k + 27 = 25
37 + 4k = 25
37 - 25 = 4k
12 = 4k
k = 12 / 4
k = 3
3)4x/7－x/3=5
12x / 21 - 7x / 21 = 5
5x/21 = 5
5x =105
x = 21

4)1/4(x+17)=1/6(43－x)
x / 4 + 17 / 4 = 43 / 6 - x / 6
3x / 12 + 2x /12 = 86 / 12 - 51 / 12
5x / 12 = 35/12
x = 7

1). 24-9=5x-2x
15=3x
x=5

2). 10-2k+6k+27=25
4k=25-10-27
4k=-12
k=-3

3). 3(4x)/21-7x/21= 5
12x/21-7x/21=5
5x/21=5
5x=21*5
x=21

4). 12[1/4(x+17)]= 12[1/6(43-x)]
3(x+17)= 2(43-x)
3x+51= 86-2x
5x=35
x=7

因為問功課的人認為知識+能幫他們解決問題,
其實抄功課反而害了自己,
還違反了知識+ 原本的意義。
知識+ 是幫我們解決問題,
但問功課是濫用了它,
知識+像十萬個為什麼般,
為我們解決日常生活的問題。

功課的作用是想幫我們練習,
並不是叫我們抄。
做功課是讓我們[拱]固基礎,温習,
抄功課就違反了這個原則。

我極力反對去補習班,
因為補習老師只是寫下答案供你抄,
不能學到任何東西。

1)24+2x=5x+9
2x+15=5x
15=3x
x=5

2)2(5－k)+3(2k+9)=25
10+2k+(3*2k+27)=25
2k+3*2k+27=15
8k+27=15
8k=-13
k=-13/8

3)4x/7－x/3=5
12x/21－7x/21=5
5x/21=5
5x=105
x=21

1)24+2x=5x+9
24-9=5x-2x
15=3x
x=5

2)2(5－k)+3(2k+9)=25
10-2k+6k+27=25
4k=25-27-10
4k=-12
k=-3

3)4x/7－x/3=5
4x/7*7-x/3*7=5*7
4x-7x/3=35
4x*3-7x/3*3=35*3
12x-7x=105
5x=105
x=21

4)1/4(x+17)=1/6(43－x)
1/4(x+17)*4*6=1/6(43-x)*4*6
6(x+17)=4(43-x)
6x+102=172-4x
6x+4x=170-102
10x=68
x=6.8