PP-T2-DS198

[Huang Hsin-Yi]

198. 19116-!-item-!-187;#058&012496
If @ denotes one of the four arithmetic operations addition, subtraction, multiplication and division, what is the value of 1 @ 2 ?

(1) n @ 0 = n for all integers n.

(2) n @ n = 0 for all integers n.

Ans:B

我想問(2)選項

"0" 如何排除?

[pigeon]

我想重點是 "for all integers n" 這一個條件吧! 雖然 n=0 都滿足 0+0=0 & 0-0=0, 但要 "for all integers n" 都成立的話,就只有 subtraction 才符合了!

[Huang Hsin-Yi]

腦筋轉過來了,謝謝!!!