Tính các tích phân sau: a) \(\int\limits_1^4 {\left( {{x^3} - 2\sqrt x } \right)dx} \); b) \(\int\limits_0^{\frac{\pi }{2}} {\left( {\cos x - \sin x} \right)dx} \); c) \(\int\limits_{\frac{\pi }{6}}^{\frac{\pi }{4}} {\frac{{{{\sin }^2}x}}} \); d) \(\int\limits_1^{16} {\frac{{\sqrt x }}dx} \).

Tính các tích phân sau:

a) \(\int\limits_1^4 {\left( {{x^3} - 2\sqrt x } \right)dx} \);

b) \(\int\limits_0^{\frac{\pi }{2}} {\left( {\cos x - \sin x} \right)dx} \);

c) \(\int\limits_{\frac{\pi }{6}}^{\frac{\pi }{4}} {\frac{{{{\sin }^2}x}}} \);

d) \(\int\limits_1^{16} {\frac{{\sqrt x }}dx} \).