maths mc 問題

The above one has got something wrong.

圖片參考：http://i238.photobucket.com/albums/ff245/chocolate328154/Maths240.jpg?t=1209970294



2008-05-05 15:13:14 補充：
Sorry that I missed out the explanation of series (II), plx press reload for the revised answer.

2008-05-06 20:05:12 補充：
http://hk.knowledge.yahoo.com/question/question?qid=7008050501024
大家快來評評理呀!!!

Let a,b,and c be positive inters.which of the folloeing must be arithmetic sequences?

I a 10, 2a 7 , 3a 4 , 4a 1 the common difference is (a-3)
II 8^b - 1 , 8^2b - 2 , 8^3b - 3, 8^4b - 4 , no common difference
III. logc^3,logc^8,logc^13,logc^18
they are (3logc,8logc,13logc,18logc) the common difference is (5logc)

A.I,II
B,I,III
C,II,III
D,I,II,III
Therefore,the answer is (B)





Let Obe a origin . if the coordinates of point A and B are ( 48,0) and (24,18)
respectively,
then the y-coordinate of the orthocemtre of 三角形ABC is

A. -7
B.6
C.8
D.32
you can find that OB=BA and the angle OBA is bigger than 90 degrees so the x-coordinate is 24 and the y-coordinate must be bigger than 18 Only (D) would be the answer

e?! 今日maths 條mc 黎嫁喎
ap 個題我choose 左 C
因為(i) 2a+7 - a+10 唔等如3a+4 - a+10