Moderate# Times When Particle Is at Rest

APCALC-VJUKRG

A particle moves in the $xy$-plane according to the equations $x( t ) ={ ( t-1 ) }^{ 2 }( t-4 ) $ and $y( t ) = \cfrac{1}{3}t^3 -\cfrac{5}{2}t^2+6t$.

Find all values of $t$ when the particle is at rest.