Question 877947
Easier would be to factor 2 out first: 2(x^2 + (3/2)x - 9/2)


Since half of 3/2 is 3/4, we want it to look something like 2(x + 3/4)^2 + constant. 2(x + 3/4)^2 has a constant term of 2*(3/4)^2 = 9/8, and we want 9, so add 63/8.


Completed square form: 2(x + 3/4)^2 + 63/8 (can be checked via Wolfram Alpha)