Each entry in the multiplication table above is an integer that is either positive, negative,or zero. What is the value of a?
(1)h≠0
(2)c=f
Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
EACH statement ALONE is sufficient.
Statements (1) and (2) TOGETHER are NOT sufficient.
注意c=0的情况,此时a的值不确定;因此只有两个条件结合才可
条件1: c不等于0
条件2: ca = c
1+2可以知道a=1,做题时误看a=0的情况了,a=0的话只在ca=a的情况成立...
已知c*a=c, 求a,有两种情况:
(1)c不等于0时,a=c/c=1
(2)c等于0时,c=0.a等于任何数
注意零的特殊情况
什么特殊情况啊?选的B。。
条件2: c=f
a*c=f
c*(a-1)=0
c=0或a=1, insufficient
谢谢呀
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