[tex]\bf -8=2(x+9)^2\implies -8=2(\stackrel{\mathbb{F~O~I~L}}{x^2+18x+81})\implies \cfrac{-8}{2}=x^2+18x+81 \\\\\\ -4=x^2+18x+81\implies 0=\stackrel{\stackrel{a}{\downarrow }}{1}x^2\stackrel{\stackrel{b}{\downarrow }}{+18}x\stackrel{\stackrel{c}{\downarrow }}{\boxed{+85}}[/tex]