Tính:
a) \(\int\limits^1_0\left(x^6-4x^3+3x^2\right)dx;\) b) \(\int\limits^2_1\dfrac{1}{x^4}dx\); c) \(\int\limits^4_1\dfrac{1}{x\sqrt{x}}dx\);
d) \(\int\limits^{\dfrac{\pi}{2}}_0\left(4\sin x+3\cos x\right)dx\); e) \(\int\limits^{\dfrac{\pi}{2}}_{\dfrac{\pi}{4}}\cot^2xdx\); g) \(\int\limits^{\dfrac{\pi}{4}}_0\tan^2xdx\);
h) \(\int\limits^0_{-1}e^{-x}dx\); i) \(\int\limits^{-1}_{-2}e^{x+2}dx\); k) \(\int\limits^1_0\left(3.4^x-5e^{-x}\right)dx\).