【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.
' _" W9 Q. G# o4 c. P. ]
' Y8 L0 G3 t$ k% N4 sIf , which of the following statements must also be true?
! \$ P0 h8 v/ @' Y
; L: G2 `. _1 ~2 h .

.
/ R. }; d& x9 y# |5 }* r0 ~
6 y1 `% L( W4 [( ?1 ]7 }( |
3 ~3 ?% l2 D4 p3 `: Q' |
.




6 P$ c, n* |2 {2 P4 s  s% j
4 o/ V0 \3 W, u$ C/ CA. None
/ `" E3 p9 J( E
B.   only
% t/ i+ O7 Q" C: w
7 a4 q: B6 q/ A7 ]" JC.   only

D.   only

" v. ]2 ?1 w  VE.   and  
. O  G* t* f+ b# V
正确答案:E

解析:

The quantity   can be expressed as  .
If , then  and  .
Since  , either   or or both. Therefore,
statement must be true, but statement , ,
is not always true. For statement , you can write
! P7 t& K) k. ?3 r1 f, and since ,
7 P- r  \& M) iit follows that .
1 w* i6 S% p- ], a; j: P& cTherefore, both statements and must be true.