new one

lovery

The Odds of Evens (number properties data sufficiency)

If a and b are both positive integers, is b^a+1 – ba^b odd?

(1) a + (a + 4) + (a – 8) + (a + 6) + (a – 10) is odd

(2) b³ + 3b² + 5b + 7 is odd  

(A) Statement (1) ALONE is sufficient to answer the question, but statement (2) alone is not.
(B) Statement (2) ALONE is sufficient to answer the question, but statement (1) alone is not.
(C) Statements (1) and (2) TAKEN TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient.
(D) EACH statement ALONE is sufficient to answer the question.
(E) Statements (1) and (2) TAKEN TOGETHER are NOT sufficient to answer the question.

ppbb

A?

12345678912345

选D啦

howardwang

B

tropicalfish

B

zimmer5

选D吧

因为1)式=5a-8 odd , then a odd

原式b(b^a-a^b)  when b odd, then (b^a-a^b) even   thus b (b^a-a^b)  even

                         when b even, then b (b^a-a^b) even

nn对不？

[此贴子已经被作者于2005-11-9 1:25:13编辑过]

boborich

D

beibeizhu

D.

两个条件最终的结果:b(b^a-a^b)都是偶数.

寂寞的声音

D:

由条件1）可以算出a是odd， 带回b(b^a - a^b) 在b为odd/even的两种情况下， 结论一致，为odd

由条件2）可以算出b是even，带回b(b^a - a^b) 在a为odd/even的两种情况下， 结论一致， 为even