*DS: X^3- 4X>0, what's the solution for X? A. -2<X<2 B. forgot C. forgot D. forgot E. X>2 or X<-2 - 應該是E- function can be reduced to X(X+2)(X-2)>0, and 函數開口向上 *PS: There's a set S that contains x numbers. How much greater the sum of S is in percentage than the mean of S? - 選項中有 100x%, (x-1)100%, and others (i forgot). 我選(x-1)100% 第一道我算的x值域是 x>2 或者 -2<x<0 不知道楼主怎样算的 第二道 我不会做 哪位tx能帮帮忙 -- by 会员 bwxz (2009/12/23 12:05:13)
第一題你應該是對的...那我考試時選錯了. 請其他NN確認 第二題: lets say the mean of S is m, so sum of S=xm. sum of S is greater than the mean of S by: (xm-m)/m= m(x-1)/m= (x-1). In percentage this equals 100*(x-1)%. |