# What is f(-4) when f(x)=-x^2-2x?

You must replace $x$ by $- 4$ into $f \left(x\right)$
if $f \left(x\right) = - {x}^{2} - 2 x$ for any value of $x$, then $f \left(- 4\right) = - {\left(- 4\right)}^{2} - 2 \cdot \left(- 4\right) = - \left(16\right) - \left(- 8\right) = - 16 + 8 = - 8$