询问数学GWD3中的一道题 大家帮解答一下

jingqitao

Q5:

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.

题目中的公式可简化为5（y-1）=r（y-1） （1）r=+-5

等于5时得不出答案 但是等于-5时y可以等于1啊

答案给出选E

我认为选A

请大家帮解答

谢谢~~~

jingqitao

panda2133

Y不能等于1吧，y＝1时原公式两边都为0了

OliverJ

答案求不出来类。。。  不用知道R     原等式中  Y 全部被约掉~

jingqitao

谢谢楼上两位的回答~