Question 442646
Divide the x coefficient by 2, then square the resulting number to get 64, so that


*[tex \LARGE x^2 + 16x + 64 = (x+8)^2]


This is because *[tex (x+a)^2 = x^2 + 2ax + a^2]. It can be seen that given the x coefficient 2a, we divide by 2 then square it.