请教一道数学题

(1)     2y – x = x² – y²

(2)     x is an odd integer.

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.

答案是A

我选了C

搞不明白[1]是怎么能求出来Y是偶的整数的.......请求帮忙解决,十分感激

还有一题不太明白:

If $1,000 will be deposited in a bank account and I is the dollar amount of interest earned from the original deposit, represented as I = 1000 {(1 + r/100)ⁿ – 1}, and the annual interest rate is r percent, is r > 8 percent?

(1)   The deposit earns a total of $210 in interest in the first 2 years.

(2)     (1 + r/100)² > 1.15

答案是each one is sufficient

第一个我知道，可是第二个有点疑问，若要满足r>8,那么
                (1 + 8/100)² > 1.166．．．不是么?这样的话[2]充分么?

不明白,求教高手....

我今天在模考软件上做到这道题目了,答案确实是A,  GWD上答案错了,呵呵