Question 41078
For 
9x^2 + 12xy + 4y^2 + 25
I'm thinking it's supposed to be -25 at the end, but if this is correct, we have
9x^2 + 12xy + 4y^2 + 25 =
(3x + 2y)^2 + 25 =
(3x + 2y - 5i)(3x + 2y + 5i)