【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.

If , which of the following statements must also be true?
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.
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1 p) x' o% ]- b0 `7 Y6 DB.   only
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4 {9 U5 w2 d! k6 Q  X8 ]  n8 rC.   only

D.   only
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E.   and  

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  `) q$ \( X* d9 R: E9 ?+ \0 c$ T解析:

The quantity   can be expressed as  .
If , then  and  .
7 G& W0 c, C7 }- R7 v: U$ kSince  , either   or or both. Therefore,
statement must be true, but statement , ,
- y% g+ h9 M; t9 U. l2 D: S+ w5 nis not always true. For statement , you can write
# K" j4 U3 Y$ B, G! |- o& U! t, and since ,
it follows that .
. e$ D3 _; o$ ^8 y, S2 r7 y& \Therefore, both statements and must be true.
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