GMAT数学考试疑问～～～

james916

在数学题，特别是DS题中，是否牵能算出正负数两个答案的都不算
如 GWD26-Q23:
If x2 – y = w（2为x的指数）, what is the value of x?
(1)    w + y = 4
(2)     y = 1
    
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.
                                                        Answer: 我选的A，因为通过（1）可算出x为正负2，但答案是E
求大神讲解一下，很疑惑

zjzw1988

求的是the value of x,所以答案只有一个~
1和2都不充分