Question 1137983
This is vertex form, so the vertex is (-h, k), where h is the number in parentheses and k is the constant.  If the vertex is (-4, 18), we know that the minimum is above the x-axis and any roots will be imaginary.
It is also part of completing the square, which we use to solve:
to solve
(x+4)^2=-9
x+4=+/- 3i,taking square root of both sides 
x=-4+/-3i, are the two roots.
{{{graph(300,300,-10,10,-10,100,2(x+4)^2+18)}}}