中一數學一問

1.20/3
2.111/37
3.3
4.-8
5.-6
6.-128/27
1/3代表3分之一

答案你自已做
1. 3y + 8 = 6y - 12
3y = 6y - 12 - 8
3y - 6y = -12 - 8
-3y = -20
y = ?

2. 102 - 5y = 32y - 9
102 + 9 - 5y = 32y
111 = 32y + 5y
111 = 37y
y = ?

3. 12y + 3 = -10y + 69
12y + 10y + 3= 69
22y = 69 - 3
22y = 66
y =?

4. 6x - 5 = 8x + 11
6x = 8x + 11 + 5
6x - 8x = 16
-2x = 16
x = ?

5. 1.2 - 0.4 = 0.2(12 - x)
1.2 - 0.4x = 2.4 - 0.2x
1.2 - 2.4 = 0.2x + 0.4x
-1.2 = 0.2x
x = ?

6. 7(x - 3 + 12) =5[7 - 4(x + 5)
7x - 21 + 84 = 35 - 20(x + 5)
7x - 21 + 84 = 55(x + 5)
7x - 21 + 84 = 55x + 275
-21 + 84 - 275 = 55x - 7x
x = ?

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1. 3y+8=6y-12
3y-6y =-12-8
-3y=-20
y=20/3
y=6/2/3

2. 102-5y=32y-9
-5y-32y=102+9
-37y=111
y=-3

3. 12y+3=-10y+69
12y+10y=69-3
22y=66
y=3

4. 6x-5=8x+11
6x-8x=11+5
-2x=16
x=-8

5. 1.2-0.4x=-0.2(12-x)
1.2-0.4x=2.4-0.2x
-0.4x+0.2x=2.4-1.2
0.2x=0.2
x=1

6 7[(x-3+12]=5[7-4(x+5)]
7(x+9)=5(7-4x-20)
7x+63=35-20x-100
7x+20x=35-100-63
27x=-128
x=4/20/27


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1. 3y+8=6y-12
3y-6y = -12-8
-3y = -20
y= 20/3

2.102-5y=32y-9
-5y-32y= -9-102
-37y= -111
y=111/37
y=3

3 .12y+3=-10y+69
12y+10y=69-3
22y=66
y=3

4 .6x-5=8x+11
6x-8x=11+5
-2x=16
x= -8

5. 1.2-0.4x=-0.2(12-x)
1.2-0.4x= -2.4+0.2x
-0.4x-0.2x= -2.4-1.2
-0.6x= -3.6
x=6

6. 7[(x-3+12]=5[7-4(x+5)]
7x-21+84=35-20x-100
7x+20x=35-100+21-84
27x=-128
x=-128/27

1. 3y+8=6y-12
8+12=6y-3y
20=3y
y=20/3

2.102-5y=32y-9
102+9=32y+5y
111=37y
y=3

3.12y+3=-10y+69
12y+10y=69-3
22y=66
y=3

4.6x-5=8x+11
6x-8x=11+5
-2x=16
x=-8

5.1.2-0.4x=-0.2(12-x)
12-4x=-2(12-x)
12-4x=-24+2x
12+24=2x+4x
36=6x
x=6

6.7[(x-3+12]=5[7-4(x+5)]
7(x+9)=5(7-4x-20)
7x+63=5(-4x-13)
7x+63=-20x-65
7x+20x=-65-63
27x=-128
x=-128/27