A ball is rolling along the $$x$-$axis. Its position $($in feet$)$ at time$$x $($in seconds$)$ is given by$()=2$ Find its instantaneous rate of change when x$=9$ seconds.

Select one:

a$.$

$6$ft$/$sec

b$.$

$1/12$ft$/$sec

c$.$

$1/3$ft$/$sec

d$.$

$2/3$ft$/$sec