Use chain rule on the first problem.
dy=sec2((3t)1/2) (1 / 2)(3t)(-1/2) (3)dx ;
dy = 3sec2((3t)1/2) / 2(3t)1/2 dx
For the second problem use quotient rule
dy = [(-2v)(5+v2)-(5-v2)(2v)] / (5+v2)2 dx
dy=(-10v-2v3-10v+2v3) / (5+v2)2dx
dy = -20v / (5+v2)2dx

Fabian C.
10/27/20