f$($x$)=\backslash$sqrt$(8-2$x$),$ what is f$^(\text{'})($x$)?$

f$^(\text{'})($x$)=(-1)/((8-2$x$)^(-0\mathrm{.}5))$

f$^(\text{'})($x$)=-(1)/(\backslash$sqrt$(8-2$x$))$

f$^(\text{'})($x$)=(1)/(2\backslash$sqrt$(8-2$x$))$

f$^(\text{'})($x$)=(-2)/((8-2$x$)^(-0\mathrm{.}5))$