【SAT每日一】7/23/12 Mathematics > Standard Multiple Choice

滚吧肥汤圆UID：3272378

Read the following SAT test question and then click on a button to select your answer.
3 `* h9 o2 n/ Z! X. F: ]. Y
If , which of the following statements must also be true?
, }% o5 o0 Q: ]8 C# u8 ~
.

, h; e/ I: P7 M .

* V( @8 b- b2 }3 R# e
# {5 Q; n1 T) U. d$ k
.

4 w0 Z7 u% E, o; f4 d


: R; \8 s! l3 C; p+ d: e, x* j. G
A. None

B.   only

C.   only

D.   only

E.   and  
! [+ v5 [7 r4 J6 N+ I
正确答案:E
5 |% Q9 d; M: N3 }1 p- @, n* n* }
( e. N% C. f  y+ |0 r# e# y解析:

The quantity   can be expressed as  .
$ @1 i- s% a; k8 k, G+ ~$ `  KIf , then  and  .
+ e$ V3 ?4 f3 P. `& XSince  , either   or or both. Therefore,
8 e! g  d. U6 q6 ^( L0 estatement must be true, but statement , ,
+ P  Y( {8 W$ Z" w; lis not always true. For statement , you can write
, and since ,
9 T; }3 \9 U: j. D  ]0 Z5 K3 pit follows that .
* J7 [) k4 d' @0 e  m, \4 eTherefore, both statements and must be true.