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题库 / Prep2007E1-DS-35
If p and n are positive integers and p > n, what is the remainder when p2 - n2 is divided by 15 ?
(1) The remainder when p + n is divided by 5 is 1.
(2) The remainder when p - n is divided by 3 is 1.
Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
EACH statement ALONE is sufficient.
Statements (1) and (2) TOGETHER are NOT sufficient.
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设5a+1=p+n, 3b+1=p-n 所以(5a+1)*(3b+1)=p2-n2=15ab+5a+3b+1=15ab+2p-1，不知道2p，不充分。
这题难道不是分解成（p+n）＊（p－n）／3*5余数是2吗
有可能p-n能整除5，p+n能整除3
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