Q19:

For each positive integer n, the integer n^* is defined by n^* = n² + 1.  What is the value of the positive integer k ?

(1)   When k is divided by 4, the remainder is 1.

(2)   18 ≤ k^* ≤ 36

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.

其实不要考虑得太多，选项（1）只说明K可以表示成 k=4x + 1的形式，问能否确定K=？？（根本和K*的运算没有关系。）---不能确定K。 选项（2）中可以带入公式得到K^2的范围，好像是17到35，这个区间中只有25是平方数---可以确定K=5

我的答案：B