Which of the following can be equal to zero?
I. M ☼ N
II. (M+N) ☼ N
III. M ☼ (M+N)
I. M ☼ N
II. (M+N) ☼ N
III. M ☼ (M+N)
-
Note that M ☼ N = MN - N = N(M - 1) = 0 whenever M = 1.
Next, (M+N) ☼ N = (M+N)N - N = N((M+N) - 1) = 0 only when M + N = 1, which can not occur since we need both M, N > 0.
Finally, M ☼ (M+N) = M(M+N) - (M+N) = (M+N)(M - 1) = 0 whenever M = 1.
So, both I and III are the answers.
I hope this helps!
Next, (M+N) ☼ N = (M+N)N - N = N((M+N) - 1) = 0 only when M + N = 1, which can not occur since we need both M, N > 0.
Finally, M ☼ (M+N) = M(M+N) - (M+N) = (M+N)(M - 1) = 0 whenever M = 1.
So, both I and III are the answers.
I hope this helps!