
David W. answered 04/04/20
Experienced Prof
First, to help you "figure out" the sign of c2, for example, if c = (-1), then +(-1)(-1) = 1.
Also, all squares are positive. This applies to c2 and to (ab)2. Let's get that out of the way and limit the possible answers to either A or B.
Now, we may concentrate on odd/even.
- Since c is even, c2 is even.
- Since a is odd and b is odd, then ab is odd. Since ab is odd, (ab)2 is odd. [note: if 2 is not a factor of a and 2 is not a factor of b, then 2 is not a factor of a*b and 2 is not a factor of a*a*b*b.].
What, then, is odd + even? You may consider the fact that odd numbers are always an even distance apart. odd + even = odd
Answer A.