For f$($x$)=$ x$^3-$ ax $($assume a is positive. this is a one$-$parameter family of functions$)$

Graph f$($x$)$ using three different values for a$.$

Using your graph in part $($a$),$ describe the critical points of f and how they appear to move as a increases.

Find a formula for the x$-$coordinates of the critical point$($s$)$ of f in terms of a$.$