Resposta :
[tex]\Large\boxed{\begin{array}{l}\sf h(t)=10+120t-5t^2\\\sf o~tempo~que~\acute e~necess\acute ario~para~atingir\\\sf a~altura~m\acute axima~ocorre~no~t_V.\\\sf t_V=-\dfrac{b}{2a}\\\\\sf t_V=-\dfrac{120}{2\cdot(-5)}\\\\\sf t_V=\dfrac{12\backslash\!\!\!0}{1\backslash\!\!\!0}\\\sf t_V=12~s\end{array}}[/tex]