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陆将除非

请大家看看这几题如何解答

Company S produces two kinds of stereos:  basic and deluxe.  Of the stereos produced by Company S last month,  were basic and the rest were deluxe.  If it takes as many hours to produce a deluxe stereo as it does to produce a basic stereo, then the number of hours it took to produce the deluxe stereos last month was what fraction of the total number of hours it took to produce all the stereos?

 

 

 

a7/17       b14/31       c7/15      d17/35       e1/2.    

 

If 5^x – 5^{x - 3} = (124)(5^y), what is y in terms of x?

                                    

                                    

                                    

                                     A.   X 

B.     x - 6

C.     x - 3

D.     2x + 3

E.      2x + 6

lingri88

第一题题干应该少了 2/3were basic and the rest were deluxe. If it takes 7/5as many hours to produce a deluxe stereo as it does to produce a basic stereo

设basic的为b,deluxe的为d,b=2d,生产d的一共(b/2)*7/[(b/2)*7+b*5]=7/17

第二题 5^x*5-5^x=5^3*5^y*124

       124*5^x=5^(3+y)*124

       y=x-3

AlphaBeta

agree  up !!!!!!!!

thumbwings

QUOTE:

以下是引用lingri88在2008-4-9 20:33:00的发言：

第一题题干应该少了 2/3were basic and the rest were deluxe. If it takes 7/5as many hours to produce a deluxe stereo as it does to produce a basic stereo

设basic的为b,deluxe的为d,b=2d,生产d的一共(b/2)*7/[(b/2)*7+b*5]=7/17

第二题 5^x*5-5^x=5^3*5^y*124

       124*5^x=5^(3+y)*124

       y=x-3

妙阿