Tính nguyên hàm

P

phamminhkhoi

đặt t = tan[TEX] \frac{x}{2}[/TEX]




------> dt = [TEX](t^2 + 1) dx[/TEX]

----> dx =[TEX]\frac{2dt}{1 + t^2}[/TEX]

sin x =[TEX] \frac{2t}{1+ t^2}[/TEX]

Cos x = [TEX]\frac{1-t^2}{1+t^2}[/TEX]



----> I = [TEX]2\int\frac{dt}{(\frac{2t}{1 + t^2} + \frac{1-t^2}{1+t^2} + 1). (t^2 + 1)}[/TEX]

= [TEX] \int\frac{2dt}{2t+2}[/TEX]

Ok hen;)
 
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