Consider the function f(t)=4sec2(t)10t3\displaystyle {f{{\left({t}\right)}}}={4}{{\sec}^{{2}}{\left({t}\right)}}-{10}{t}^{{{3}}}.

Let F(t)\displaystyle {F}{\left({t}\right)} be the antiderivative of f(t)\displaystyle {f{{\left({t}\right)}}} Then
F(t)\displaystyle {F}{\left({t}\right)} =  

Make sure you're using the correct variable.