Question 554159
-2x + a: Note that -2x is always even. Therefore a must be an odd integer.


-ax^2: x^2 is nonnegative, so -x^2 is non-positive; setting *[tex \LARGE a \le 0] makes the expression nonnegative.


3x + a: 3x is already divisible by 3, so a must also be divisible by 3.