GWD 11-34

What is the value of the integer n?

(1) n(n + 2) = 15

(2) (n + 2)ⁿ = 125

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

请教思路 答案应该是B 但如果比较正规推出B

谢谢

What is the value of the integer n?

(1) n(n + 2) = 15

(2) (n + 2)ⁿ = 125

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

请教思路 答案应该是B 但如果比较正规推出B

谢谢

如果是我做这题 我肯定是通过举反例

条件1）n＝－5 或者3

条件2） 125 为5的三次方 没有别的整数可以找到了 所以n只能等于3

看来只能一个一个试试了，

哦，对了，是不是可以通过单调递增的原理推出来B？？？

thanks !!