Ответ: [tex]x(t)=3t-0.04t^3 \\\\ v(t)=x'(t)=3-0.12t^2 \\\\ 3-0.12t^2=0 \\\\ 0.12t^2=3 \\\\ t^2=25 \\\\ t=5 \\\\ a(t)=v'(t)=-0.24t \\\\ a(5)=-0.24*5=-1.2[/tex]