Clarify your complex basic!
\[\large x^2 + 18x + 90 = 0\]
Find the value(s) of \(x\) satisfying the equation above.
If the answers are of the form \(-ai - b\) and \(ai - b\), with positive \(a\), submit your answer as \(a+b\).
Bonus: Try to solve it without using the quadratic formula.