D, this question is basically asking which numbers in the set {2, 4, 6, 8, 10} is greater than 10 WHEN 5 is added. To solve this, just look at each number and add 5, if the result is greater than 10 then it is in the answer if not then it is not. Hope this helped!
Your answer is -2 as the axis of symmetry is at -b/2a. So if you were to expand the equation, you would get y= x^2/4 +x -6 where b is 1 and 2a is ½ . Therefore -1 / ½ gives you -2
