ai help mình nha

T

thong1990nd

[TEX]\int_{}^{}(cos^2x/sinx+\sqrt[2]{3}cosx)dx[/TEX]
Câu 2
cho [TEX]f(x)= sin2x/(2+sinx)^2[/TEX]
tìm A, B để
[TEX]f(x)= Acosx/(2+sinx)^2+Bcos/(2+sinx)[/TEX]
@-)@-)@-)@-)@-)@-)@-)@-)@-)
đề như trên ah bạn:p...........................,,,,,,,,,,,,,,,,,,,,
1) [TEX]=\int_{}^{}\frac{cos^2x}{sinx}dx+\sqrt[]{3}\int_{}^{}cosxdx[/TEX]
[TEX]=\int_{}^{}\frac{dx}{sinx}-\int_{}^{}sinxdx+\sqrt[]{3}\int_{}^{}cosxdx[/TEX]
[TEX]=\frac{1}{2}\int_{}^{}\frac{dx}{tan\frac{x}{2}.cos^2\frac{x}{2}}+cosx+\sqrt[]{3}sinx[/TEX]
[TEX]=ln|tan\frac{x}{2}|+cosx+\sqrt[]{3}sinx+C[/TEX]
2) [TEX]sin2x/(2+sinx)^2=\frac{Acosx}{(2+sinx)^2}+\frac{Bcosx(2+sinx)}{(2+sinx)^2}[/TEX]
[TEX]=\frac{(A+2B)cosx+\frac{B}{2}sin2x}{(2+sinx)^2}[/TEX]
đồng nhất [TEX]\left{\begin{A+2B=0}\\{\frac{B}{2}=1}[/TEX]
\Rightarrow [TEX]\left{\begin{A=-4}\\{B=2} [/TEX]:eek:
 
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