【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.

4 i+ d# c4 V$ f) w# b4 ]4 KIf , which of the following statements must also be true?
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/ O! [0 @, r) L6 G4 p .

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) C# [& u; V. I; N- W2 ` .



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A. None
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) w: _. Z; s7 B; v5 HB.   only
% [( M$ N3 C: K$ l. H; W$ o9 s
C.   only
- b, N6 E1 D9 ~7 G% W+ }3 k1 F
% S$ w. H: o1 y, P: ^6 Y2 W! v8 UD.   only

E.   and  

' B& s: ~9 {/ a+ m4 V9 r  a7 t& `4 W5 t  R正确答案:E
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解析:

9 r) n- n) L! s) m/ v8 Z" Q8 ]! TThe quantity   can be expressed as  .
. e# B3 L. X! A. T9 F% ^' d% BIf , then  and  .
3 V- c7 H* N% H2 O! HSince  , either   or or both. Therefore,
statement must be true, but statement , ,
* a) b# t% E4 Y# z. Tis not always true. For statement , you can write
, and since ,
# _3 h" h% K7 V4 c* wit follows that .
Therefore, both statements and must be true.

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