Solución

Apartado a

v(t)=6t230t+36v\left( t \right) = 6{t^2} - 30t + 36, a(t)=12t30a\left( t \right) = 12t - 30

Apartado b

Crece en (2,2.5)(3,)\left( {2,2.5} \right) \cup \left( {3,\infty } \right), decrece en (0,2)(2.5,3)\left( {0,2} \right) \cup \left( {2.5,3} \right)