求助GWD一道题

evelyn205205

If (y+3)(y-1) – (y-2)(y-1) = r(y-1), what is the value of y?
(1)r² = 25
(2)r = 5

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 IS E
不懂为什么

沉睡的巨人

等式左边提取公因式=(y-1)(y+3-y+2)=5(y-1)
5(y-1)=r(y-1) 显然无法得知y的值