數學~已知答案~求計算過程?

2008-09-19 7:21 am
已知答案~求計算過程?
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1. A= ( A / 1.5 - 8000 ) + 1.5 ( A / 1.5 - 8000 )
答案 A = 48000
2. X + 3600 - 2X = X/3  
答案 X = 2700  X/3=900
謝謝!
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回答 (2)

2008-09-19 6:24 pm
✔ 最佳答案
1. A=[ ( A / 1.5) -8000 )]+ 1.5 [( A / 1.5)- 8000 ]
A=[ ( A / 1.5) -8000 )]+A-12000
1.5*A=1.5*{[ ( A / 1.5) -8000 )]+A-12000}
1.5A=A-12000+1.5A-18000
A+1.5A-1.5A=12000+18000
A=30000

驗算:
答案:A=30000
右式=[ ( A / 1.5) -8000 )]+ 1.5 [( A / 1.5)- 8000 ]
=[(30000/1.5)-8000]+1.5[(30000/1.5)-8000]
=(20000-8000)+1.5(20000-8000)
=12000+1.5*12000
=12000+18000
=30000
左式=A=30000
左式=右式

答案:A=48000
右式=[ ( A / 1.5) -8000 )]+ 1.5 [( A / 1.5)- 8000 ]
=[(48000/1.5)-8000]+1.5[(48000/1.5)-8000]
=(32000-8000)+1.5(32000-8000)
=12000+1.5*12000
=24000+36000
=60000
左式=A=48000
左式≠右式

2. X + 3600 -2X = X/3 
(X/3)+2X-X=3600
[(1+6-3)/3]X=3600
(4/3)X=3600
X/3=3600/4=900
X=900*3=2700

答案 X = 2700  X/3=900
參考: Me算
2008-09-19 7:40 am
1. A= ( A / 1.5 - 8000 ) + 1.5 ( A / 1.5 - 8000 )

A = A / 1.5 -8000 + A - 12000

(等號兩邊同乘以1.5)

1.5A = A - 12000 + 1.5A -18000

1.5A = 2.5A - 30000

-A = -30000

所以 A = 30000

(Ps: 答案 A = 48000 , 是錯的)


2. X + 3600 - 2X = X/3

3600 - X = X /3

(等號兩邊同乘以3)

10800 - 3X = X

10800 = 4X

10800 / 4 = X

所以 X= 2700
參考: me


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