[問題]GWD28-34

[medi66]

Q34:
The operation Θ is defined by x Θ y = + for all nonzero numbers x and y. If z is a number greater than 1,
which of the following must be true?


I. x Θ (-z) = 0
II. z Θ = 1
III. Θ = z


A. I only
B. I and II only
C. I and III only
D. II and III only
E. I, II, and III

答案是 E

請問一下 I. x Θ (-z) = 0 怎麼會是對的呢 如何計算呢???
還是題目或是答案有問題呢??

麻煩大家了~

[medi66]

頂一下~

[skull]

cd說 可能印錯 x應為z就會對了

[medi66]

感謝~