$5.$ use the following recursive function:

int F$($int n$)$

$\{$

if $($n $==0)$

return $0$;

else return n $+$ F$($n$-1)$;

$\}$

What final value is returned from the function call F$(5)?$

What final value is returned from the function call F$(0)?$

What final value is returned from the function call F$(-1).$

Suppose $+$ is changed to $*$ in the recursive step.

What final value is returned from the function call F$(5)?$