The expression ab+a is odd when the a and b are integers. Which of the following expressions must be even? Choices
A) a  B) b  C) a + b  D) ab - a  E) a + b^2
ab+a is odd   a and b are integers   If a were even "ab+a" would be even despite any value of b.   B can't be odd, so "b" must be even.   Ans : b
<result>B</result>
The expression ab+a is odd when the a and b are integers. Which of the following expressions must be even?