F.2 mathz (MC)

1. 0.02583 m2=2.583 cm2
so the answer is A
2. x=(2- 1/a) / (2+ 1/a)
2x+ x/a=2- 1/a
2(x-1)=- 1/a (x+1)
-2(x-1) / (x+1)=1/a
a=(x+1) / 2(1-x)
so the answer is D


2007-12-19 23:21:47 補充：
I'm sorry I have made a mistake2.583 cm^2=3 cm^2 (correct to the nearest cm^2)so the answer would be B

2007-12-21 09:59:06 補充：
唔好意思, 樓上那位哥哥說得沒錯

1)Correct 0.02583m^2 to the nearest cm^2.

0.02583 m2
= ( 0.02583 * 100 ) cm2
=2.583 cm2
=3 cm2 ( Correct to the nearest cm2 )

Therefore , the ans is B .


2)Make a be the subject of the formula of x=(2-1/a)/(2+1/a)

x=(2-1/a)/(2+1/a)
(2+1/a)x=2-1/a
2x+x/a=2-1/a
a*(2x+x/a)=a*(2-1/a)
2ax+x=2a-1
2ax-2a= -1-x
2a*(x-1)= -1-x
a= -1-x/2(x-1)
a= - (1+x)/ - 2(1-x)
a=1+x/2(1-x)

Therefore , the ans is D.

2007-12-22 15:47:05 補充：
Oh yes.Sorry.The first ans should be C...( I miss one more *100 )SrySo tired .Thx for reminding me!

1 C
2 D

2007-12-19 23:23:57 補充：
第一條一定c因為 1m^2 = 1m x 1m , 1m = 100cm , 1m^2 = 1m x 1m = 100cm x 100cm = 10000cm^2所以0.02583m^2 = 258cm^2 =C

2007-12-20 18:40:09 補充：
不是針對，但下面兩位仁兄的數學真係有進步空間。可唔可以看一下我的補充資料？謝謝﹗1m^2 = 1m x 1m = 100cm x 100cm = 10000cm^2