Okay, here we have this:
[tex]x^2+11x+20=-8[/tex]Let's solve it:
[tex]x^2+11x+28=0[/tex]We are going to solve with the general formula for equations of the second degree:
[tex]x_{1,2}=\frac{-11\pm\sqrt[]{11^2-4\cdot1\cdot28}}{2\cdot1}[/tex][tex]\begin{gathered} =\frac{-11\pm\sqrt[]{121-112}}{2} \\ =\frac{-11\pm\sqrt[]{9}}{2} \\ =\frac{-11\pm3}{2} \\ x_1=\frac{-11+3}{2}=\frac{-8}{2}=-4 \\ x_{2_{}}=\frac{-11-3}{2}=\frac{-14}{2}=-7 \end{gathered}[/tex]Finally we obtain that the solutions to the equation x²+11x+20=-8 are x=-4 and x=-7.