Question $1,3\mathrm{.}2\mathrm{.}11$ Part $5$ of $14($a$)$ Find f$(-21)$ and f$(-6).\{$:$[$f$(-21)=-8],[$f$(-6)=8]$:$\}($b$)$ Find f$(18)$ and f$(0).\{$:$[$f$(18)=8],[$f$(0)=-4]$:$\}($c$)$ Is f$(6)$ positive or negative? Positive Negative $($d$)$ Is f$(-9)$ positive or negative? Positive Negative $($e$)$ For what value$($s$)$ of x is f$($x$)=0?$ x$=-18,12($Use a comma to separate answers as needed.$)$