Question 77050
{{{(x+1)(x+8)=-12}}}

{{{x^2+9x+8=-12}}} foil the left side

{{{x^2+9x+20=0}}} Add 12 to both sides

*[invoke factoring_quadratics 1, 9, 20]

So the quadratic {{{x^2+9x+20=0}}} factors to  
{{{(x+4)(x+5)=0}}}
Set each factor equal to zero
{{{x+4=0}}}
{{{x=-4}}}

{{{x+5=0}}}
{{{x=-5}}}
So our answer is 
{{{x=-4}}} or {{{x=-5}}}