Question

@triciaal @perl

Is the set of multiples of 6 closed under subtraction? Explain why or provide a counterexample if not.

A.
Yes, because the difference of any two multiples of 6 is equal to 6.

B.
Yes, because the difference of any two multiples of 6 is also a multiple of 6.

C.
No, and a counterexample is 6 – 6 = 0.

D.
No, and a counterexample is 6 – 18 = –12.

Answer 1

6 - 6 = 0 and 0 is a multiple of 6 , 6*0 = 0

6 - 12 = -6 and -6 is a multiple of 6 , 6*-1 = -6

Answer 2

A