Question

If a and b are integers and a – b is even, which of the following must always be even?
1. ab
2. a² + b² + 1
3. a² + b + 1
4. ab – b

Answer 1

Correct Answer - Option 4 : ab – b

According to the given relation of a – b = even, there is a possibility of odd-odd (or) even-even is equal to even.

From the options, Option (D) is correct.

Since, odd × odd – odd (or) even × even – even → is always even number.