mot bai tich phan

H

hoanghondo94

Gợi ý:

[TEX]\int \frac{dx}{x^4+x^2+1}=\frac{1}{2}\int \frac{(x^2+1)-(x^2-1)}{x^4+x^2+1}=\frac{1}{2}\left [ \int \frac{x^2+1}{x^4+x^2+1}dx-\int \frac{x^2+1}{x^4+x^2+1}dx \right ] \\\\=\frac{1}{2}\left [ \int \frac{1+\frac{1}{x^2}}{(x^2+\frac{1}{x^2})+1}dx -\int \frac{1-\frac{1}{x^2}}{(x^2+\frac{1}{x^2})+1}dx\right ]=\frac{1}{4}\left [ \int d\frac{(x-\frac{1}{x})}{(x-\frac{1}{x})^2+3}dx -\int d\frac{(x+\frac{1}{x})}{(x+\frac{1}{x})^2-1}dx\right ][/TEX]

Tiếp tục nhé :)
 
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