數學方程式~~急急急

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① 3 ( a 加 1 ) ＝ 15
3*(a+1)=15
3*(a+1)3=153
a+1-1=5-1
a=4


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② 3分之 1 ( a 減 6 ) ＝ 7

1/3 X (a-6)=7
1/3 X (a-6)1/3=71/3
a-6+6=21+6
a=27
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③ 6y 減 3 ( 5減 y ) ＝ 21

6y-3 X (5-y)=21
6y-3 X (5-y)+3 =21+3
6y X(5-y)6 = 246
y(5-y)=4
4y4=44
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④ ( 8y 減 9 ) 加 ( 15 減 2y ) ＝ 6 減 18

(8y-9)+(15-2y)=6-18
8y-9+15-2y=(-12)
8y-2y+6=(-12)
6y+6=(-12)
6y+6-6=(-12)-6
6y=(-18)
6y/6=(-18)/6
y=(-3)

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⑤ 4 ( 5 分之 3m ) 減 2m 減 8 ＝ 0 ，並驗算解答。

4(3m/5)-2m-8=0
12m/5-2m-8=0
2.4m-2m-8=0
0.4m-8+8=0+8
0.4m=8
0.4*2.5m=8*2.5
m=20

驗算解答:
4(3m/5)-2m-8=0
4(3*20/5)-2*20-8=0
4(3*4)-40-8=0
4*12-48=0
48-48=0


圖片參考：http://l.yimg.com/f/i/tw/ugc/rte/smiley_22.gif

① 3 ( a 加 1 ) ＝ 15

3a+3=15 （3(a+1)=3a+3*1 ex.3*(5+1)=3*5+3*1）

3a=12 <3a+3=15-->3a+3-3=15-3-->3a=15>

a=4 <3a=12-->3a/3=12/3-->a=4>

② 3分之 1 ( a 減 6 ) ＝ 7

1/3(a-6)=7

1/3*a-1/3*6=7

a/3-2=7

a/3=7+2

a/3=9

a=9*3

a=27

③ 6y 減 3 ( 5減 y ) ＝ 21

6y-3(5-y)=21

6y-(15-3y)=21

6y-15+3y=21<6y-(15-3y)-->6y-15+3y ex.5-(3-1)=5-3+1>

9y-15=21 <6y-15+3y=6y+3y-15>

9y=21+15

9y=36

y=36/9

y=4

④ ( 8y 減 9 ) 加 ( 15 減 2y ) ＝ 6 減 18

(8y-9)+(15-2y)=6-18

8y-9+15-2y=6-18<(8y-9)+(15-2y)=8y-9+15-2y e

x.(5-3)+(2-1)=5-3+2-1>

6y+6=-12

6y=-18

y=-3

⑤ 4 ( 5 分之 3m ) 減 2m 減 8 ＝ 0

4*3/5m-2m-8=0

12/5m-2m-8=0

12/5m-2m=8

2 2/5m-2m=8

2/5m=8

m=20

1. a = 4

2. a = 27

3. y = 4

4. y = -3

5. 4( 3m&divide;5) -2m - 8= 0

12m &divide;20 -2m= 8

10m= 8(20)

m = 160 &divide; 10

m = 16

① 3 ( a 加 1 ) ＝ 15
=>3(a+1)=15
=>3a+3=15
3a+3-3=15-3
3a=12
3a/3=12/3
a=4
② 3分之 1 ( a 減 6 ) ＝ 7
=>1/3(a-6)=7
=>(1/3)a-(1/3)*6=7
=>(1/3)a-2=7
=>(1/3)a-2+2=7+2
=>(1/3)a=9
=>(1/3)a*3=9*3
=>a=27
③ 6y 減 3 ( 5減 y ) ＝ 21
=>6y-3(5-y)=21
=>6y-(3*5-3y)=21
=>6y-(15-3y)=21
=>6y-15+3y=21
=>9y-15=21
=>9y-15+15=21+15
=>9y=36
=>9y/9=36/9
=>y=4
④ ( 8y 減 9 ) 加 ( 15 減 2y ) ＝ 6 減 18
=>(8y-9)+(15-2y)=6-18
=>8y-9+15-2y=(-12)
=>8y-2y+6=(-12)
=>6y+6=(-12)
=>6y+6-6=(-12)-6
=>6y=(-18)
=>6y/6=(-18)/6
=>y=(-3)
⑤ 4 ( 5 分之 3m ) 減 2m 減 8 ＝ 0 ，並驗算解答。
=>4(3m/5)-2m-8=0
=>12m/5-2m-8=0
=>2.4m-2m-8=0
=>0.4m-8=0
=>0.4m=8
=>0.4*2.5m=8*2.5
=>m=20
驗算解答:
4(3m/5)-2m-8=0
=>4(3*20/5)-2*20-8=0
=>4(3*4)-40-8=0
=>4*12-48=0
=>48-48=0
=>0=0

① 3 ( a 加 1 ) ＝ 15

3a+3=15 （3(a+1)=3a+3*1 ex.3*(5+1)=3*5+3*1）

3a=12 <3a+3=15-->3a+3-3=15-3-->3a=15>

a=4 <3a=12-->3a/3=12/3-->a=4>

② 3分之 1 ( a 減 6 ) ＝ 7

1/3(a-6)=7

1/3*a-1/3*6=7

a/3-2=7

a/3=7+2

a/3=9

a=9*3

a=27

③ 6y 減 3 ( 5減 y ) ＝ 21

6y-3(5-y)=21

6y-(15-3y)=21

6y-15+3y=21<6y-(15-3y)-->6y-15+3y ex.5-(3-1)=5-3+1>

9y-15=21 <6y-15+3y=6y+3y-15>

9y=21+15

9y=36

y=36/9

y=4

④ ( 8y 減 9 ) 加 ( 15 減 2y ) ＝ 6 減 18

(8y-9)+(15-2y)=6-18

8y-9+15-2y=6-18<(8y-9)+(15-2y)=8y-9+15-2y e

x.(5-3)+(2-1)=5-3+2-1>

6y+6=-12

6y=-18

y=-3

⑤ 4 ( 5 分之 3m ) 減 2m 減 8 ＝ 0

4*3/5m-2m-8=0

12/5m-2m-8=0

12/5m-2m=8

2 2/5m-2m=8

2/5m=8

m=20

驗算解答:

4*(3*20/5)-2*20-8

=4*12-2*20-8

=48-40-8

=0

希望可以幫到你

你的意思是算出來嗎??

1

3(A+1)=15
3A+3=1
3A=12
A=4



2

1/3(A-6)=7
A/3-2=7
A/3=9
A=27


3

6Y-3(3-Y)=21
6Y-9-3Y=21
3Y=30
Y=10


4

(8Y-9)+(15-2Y)=6-18
8Y-9+15-2Y=-12
6Y=-18
Y=-3


5

4(3m/5)-2m-8= 0
12m/5-2m=8
(12m-10m)/5=8
2m=30
m=15



希望幫到你