tính hộ mình nguyên hàm sau tks

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hanguyen445

Bạn nào hỏi bài:
[tex]{I}=\int_{0}^{ln2}\frac{2e^{3x}+e^{2x}-1}{e^{3x}+e^{2x}-e^x+1}dx=[/tex]
[tex]t=e^x[/tex]
[tex]{I}=\int_{1}^{2}\frac{2t^3+t^2-1}{t(t^3+t^2-t+1)}dt=\int_{1}^{2}\frac{-1}{t}dt-\int_{1}^{2}\frac{3t^2+2t-1}{t^3+t^2-t+1}dt=\ln\-\frac{t^3+t^2-t+1}{t}\-\[/tex]
 
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hanguyen445

Lời giải cho tích phân bạn hỏi:
[tex]{I}=\int\frac{1}{x^3(\sqrt[7]{(x^7+1)^5})}}dx=\int\frac{x^5}{x^8(\sqrt[7]{(x^7+1)^5})}dx=\int\frac{1}{x^8\sqrt[7]{(\frac{x^7+1}{x^7})^5}}dx[/tex]
[tex]u=1+\frac{1}{x^7}\rightarrow{dx}=\frac{-7}{x^8}dx\rightarrow{dx}=\frac{-x^8}{7}du[/tex]
[tex]{I}=\frac{-1}{7}\int\frac{1}{\sqrt[7]{u^5}}du=-\frac{1}{2}\sqrt[7]{u^2}+C=-\frac{1}{2}\sqrt[7]{(1+\frac{1}{x^7})^2}+C[/tex]
 
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