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[vanhieu9779]

1. $\int_{e}^{e^{2}}\frac{1}{cos^{2}(1+lnx)}dx$

2.$\int_{0}^{\sqrt{3}}\frac{tg^{4}x}{cos2x}dx$

[caovannct]

1. $\int_{e}^{e^{2}}\frac{1}{cos^{2}(1+lnx)}dx$

2.$\int_{0}^{\sqrt{3}}\frac{tg^{4}x}{cos2x}dx$

2. I = $\int \frac{tan^4x}{(1-tan^2x)cos^2x}dx$

đặt tanx = t ta thu đc $I=\int \frac{t^4}{1-t^2}dt$

Đến đây thì OK rồi