Вы ввели
Integral(x^3/cos(x^4)^2, (x, 0, 1))
1 / | | 3 | x | -------- dx | 2/ 4\ | cos \x / | / 0
$$\int_{0}^{1} \frac{x^{3}}{\cos^{2}{\left (x^{4} \right )}}\, dx$$