At time t= 0, a particle is located at the point (5,3,7). It travels in a straight line to the point (6, 1,2), has speed 4 at (5,3,7) and constant acceleration i - 2j - 5k. Find an equation for the position vector r(t) of the particle at time t. . . . The equation for the position vector r(t) of the particle at time t is r(t) = i+ j+ K . (Type exact answers, using radicals as needed.)