中一一元代數方程

1. 4-5y=-26
-5y=-30
y=6

2. 5-x/9=3
-x/9 = -2
x/9 = 2
x = 18

3. 5-y/7=3
-y/7 = -2
y/7 = 2
y = 14

4. 2(p-6)=18
p-6 = 9
p=15

5. 6(4x+11)=-30
4x+11 = -5
4x = -16
x = -4

6. 0.4n+2.9=4.1
4n+29=41
4n=12
n=3

7. 6y/13-35=-11
6y/13 = 24
6y=312
y=52

8. 1/4+n/5=20/1 <--- you mean 1/20?
but if it is 20/1,
then 1/4 + n/5 = 20
n/5 = 79/4
n = 395/4
but if it is 1/20,
then 1/4+n/5=1/20
20(1/4+n/5) = 20(1/20)
5+4n = 1
4n = -4
n = -1

9. 4(5x-1)/7=8
4(5x-1) = 56
5x-1 = 14
5x = 15
x = 3

10. 5y-11=2(y+8)
5y-11=2y+16
3y=27
y=9

11. 6(5+2x)=-4(3-x)
30+12x = -12+4x
8x = -42
x = -21/4

12. d/8-d/8=10
no solutions since d/8-d/8 = 10 => 0 = 10

13. x/4+3x/5=-2
20(x/4+3x/5) = -2
5x+12x = -2
17x = -2
x = -2/17

14. 6(x+2)-3(x-5)=24
6x + 12 - 3x + 15 = 24
3x = -3
x = -1

15. 10[(4-y)+7y]=28
10(4-y) + 70y = 28
40 - 10y + 70y = 28
60y = -12
y = -1/5

16. 2y+3/3=y-1/8
2y + 1 = y - 1/8
8(2y+1) = 8(y - 1/8)
16y + 8 = 8y - 1
8y = -9
y = -9/8

2010-01-02 13:31:46 補充：
To: kinyip1997
I dont think your answer in Q12 is correct,
since 8(d/8-d/8) = 10x8
d-d = 80
0 = 80
It should be no solutions.

1.) 4-5y=-26
-5y=26-4
-5y=22
y=22/5
y=4.4

2.) 5-x/9=3
5-x=9X3
5-x=27
-x=27-5
-x=22


3.) 5-y/7=3
5-y=7X3
5-y=21
-y=21-5
-y=16

4.) 2(p-6)=18
2p-12=18
2p=18+12
2p=30
p=30/2
p=15

5.) 6(4x+11)=-30
24x+66=-30
24x=-30-66
24x=-96
x=-96/-24
x=4

6.) 0.4n+2.9=4.1
0.4n=4.1-2.9
0.4n=1.2
n=1.2/0.4
n=3

7.) 6y/13-35=-11
6y/-22=-11
6y=(-11)X(-22)
6y=363
y=60.5

8.) 1/4+n/5=20/1
5/20+n/5=400/20
n/5=400/20-5/20
n/5=395/20
n=395/20X5
n=98.75

9.) 4(5x-1)/7=8
20x-4/7=8
20x-4=8X7
20x-4=56
20x=56+4
20x=60
x=60/20
x=3

10.) 5y-11=2(y+8)
5y-11=2y+16
5y-2y=16+11
3y=27
y=27/3
y=7

11.) 6(5+2x)=-4(3-x)
30+12x=-12+4x
12x-4x=-12-30
8x=-42
x=-42/8
x=5.25



12.) d/8-d/8=10
8Xd/8-8Xd/8=10
2d=10X8
d=80/2
d=40

13.) x/4+3x/5=-2
5x/20+12x/20=-2
17x/20=-2
7x=(20)X(-2)
7x=-40
x=-40/7
x=5.7142857142857......

14.)6(x+2)-3(x-5)=24
6x+12-3x+15=24
3x+27=24
3x=24-27
3x=-3
x=3/-3
x=-3

15.)10[(4-y)+7y]=28
10(4-y+7y)=28
10(4+6y)=28
40+60y=28
60y=28-40
60y=-12
y=60/-12
y=-5

16.)2y+3/3=y-1/8
2y + 1 = y - 1/8
8(2y+1) = 8(y - 1/8)
16y + 8 = 8y - 1
8y = -9
y = -9/8

1. y=6
2. x=18
3. y=14
4. p=15
5. x=-4
6. n=3
7. y=52
8. n=395/4
(8. n=-1)(1/20?)
9. x=3
10. y=9
11. x=-21/4
12. NO SOLUTIONS
13. x=-40/17
14. x=-1
15. y=-0.2
16. y=-9/8
(16. y=27/8)[(2y+3)/3?]