lisaislisa

(1.00001)^2*(0.99999)^2-(1.00002)^2*(0.99998)^2
My ans.：-3*(10)^(-10)
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这题在上周jj中可丫头算不到这个答案呀
哎 我怕计算的....;p

lisaislisa

to coffein
I've replied that msg

^^

lisaislisa

to mingja
两个人分别完成某项任务，A用了X小时，B比A快两倍，问in term of X,两个人一起完成这项任务要用多久? 答案是2X/3
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my ans is x/3
1/[(1/x)+(2/x)]
the ans must be wrong , since it's impossible that two of the guy spend longer time to do the things than one of the guys does

2. still number discussion , i think it is A

3某东西sell at price 20 dollors, including tax, 税率是百份P，还包括其他什么费less than C，好象问：不含税的部分小于15吗？A：P等于6，B：C等于5
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(x+c)(1+p)=20
my ans is B

4． 有一个长方形，长是12，宽是18，现在扩大多少倍？问现在的宽是多少？
A：长扩大多少倍 B：宽扩大多少倍？
答案肯定是D
agree D
(12+x)(18+y)=12*18*# ( # should be known though the problem is incomplete)

5． 有某个地方的用电量1993年是3.2million 而1993年是3.4million，他们用柱壮图来表示，用电量与柱高成正比例，1993年的柱高是2cm，问：1994年的柱高是多少？
答案：3.2/2=3.4/x x=9/4
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agree , the ratio of the height in the graph and the amount consuming is unchanged

6. A和B的家在路的两端相隔76米，A和B同时从家里出发，在离A的家36米的地方相遇，问两个人速度的比：76/(x+y)=36/x
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36/A=40/B=>A:B=9:10

^^

lisaislisa

3某东西sell at price 20 dollors, including tax, 税率是百份P，还包括其他什么费less than C，好象问：不含税的部分小于15吗？A：P等于6，B：C等于5 --------------------------------- (x+c)(1+p)=20 if c=5 , whatever p is , ( even is 0 ) x<=15 , but from the text , p can not be 0 , since there is tax payment ( or you will be fined ....kidding ) so B is sufficient but when p=6 or mean tax rate 6% x+c about 19 , x can be less or more than 15 ^^

lisaislisa

about the problem on tax fees ,
I met this problem today !
but little difference , the difference is that c is the change that recieved after paying , therefore it is
x(1+p)+c=20
I chose B , but my math is ....49  

lisaislisa

1.the fomula is (1+p)x+c=20 ans C 3.whether x<0? 1)x^3+x<0 2)x^3+x+1=0 (2次) 【确认】选D ----------------- 2)=>x(x^2+1)=-1 since (x^2+1)>0 x<0 therefore is D 4 imcomplete , i am afraid ... others , agree ^^

lisaislisa

to nobody test

1. in your fomula  C+CP%+F=20
2)=> F=5, then C must be less than 15
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therefore B is sufficient , how come you think 'B neither is sufficient then' ?

3. you are not the first to raise the question ...so far open to question

5. yours is correct

^^