Algebra Level 2

$\large x^2 + 18x + 90 = 0$

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 $$a+b$$.

Clarification: $$i=\sqrt{-1}$$.

Bonus: Try to solve it without using the quadratic formula.

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