quy nap
bai nay cung ko kho lam nhung hoi dai ban ak..hjhjhj nhung minh goi y nha
vidu nhu bai nay [TEX]I=\int\tan^6xdx[/TEX] ban ap dung ma lam qua bai kia cua ban nhe'
[TEX]\int\tan^6xdx=\int\[(tan^4x(tan^2x+1)-tan^4x]dx=\int\tan^4x(tan^2x+1)dx-\int\tan^4xdx=\int\tan^4x(tan^2x+1)dx-\int\(tan^2x(tan^2x+1)-tan^2x)dx=\int\tan^4x(tan^2x+1)\int\tan^2x(tan^2x+1)-\int\tan^2xdx[/TEX]
[TEX]t=tanx\Rightarrow dt=(1+tan^2x)dx[/TEX]
[TEX]I=\int t^4dt-\int t^2dt-\int\(1+\frac{1}{cos^2x})dx[/TEX]