It is required to find the value of the equation when x = -1
So, substitute with x = -1 at the given equation
So,
[tex]\begin{gathered} -2x^{2}-12x+5-x+8x \\ =-2\cdot(-1)^2-12\cdot(-1)+5-(-1)+8\cdot(-1) \\ =-2\cdot1+12\cdot1+5+1-8\cdot1 \\ =-2+12+5+1-8 \\ =18-10 \\ =8 \end{gathered}[/tex]