TTgwd5-7关于或或的问题

jessiebetty

Q7:

What is the value of │x + 7│?

(1)     │x + 3│= 14

(2)     (x + 2)² = 169

                  

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.

我觉得C是:11,-17,-15的并集,

应该是E吧,如何理解

lovetiky

(1) => x = -17 or 11

(2) => x = -15 or x = 11

thus from (1) and (2) together, we can assure that x = 11

荷叶田田

我怎么觉得是D呢...

比如(1),x+3的绝对值是14，那（x+7）的绝对值=（x+3）的绝对值再加4=18啊，可以不需要知道x的值的，因为4是正数嘛~

（2）也是，（x+2)^2=169,所以（x+2)的绝对值就等于13，然后方法同上啊。

请NN指教