Tính:
a) \(\int\limits^1_03^xdx;\)
b) \(\int\limits^1_0\left(2.3^x-5e^x\right)dx.\)
Tính các tích phân sau bằng phương pháp tính tích phân từng phần :
a) \(\int\limits^{e^4}_1\sqrt{x}\ln xdx\)
b) \(\int\limits^{\dfrac{\pi}{2}}_{\dfrac{\pi}{6}}\dfrac{xdx}{\sin^2x}\)
c) \(\int\limits^{\pi}_0\left(\pi-x\right)\sin xdx\)
d) \(\int\limits^0_{-1}\left(2x+3\right)e^{-x}dx\)
Hãy chỉ ra kết quả nào dưới đây đúng :
a) \(\int\limits^{\dfrac{\pi}{2}}_0\sin xdx+\int\limits^{\dfrac{3\pi}{2}}_{\dfrac{\pi}{2}}\sin xdx+\int\limits^{2\pi}_{\dfrac{3\pi}{2}}\sin xdx=0\)
b) \(\int\limits^{\dfrac{\pi}{2}}_0\left(\sqrt[3]{\sin x}-\sqrt[3]{\cos x}\right)dx=0\)
c) \(\int\limits^{\dfrac{1}{2}}_{-\dfrac{1}{2}}\ln\dfrac{1-x}{1+x}dx=0\)
d) \(\int\limits^2_0\left(\dfrac{1}{1+x+x^2+x^3}+1\right)dx=0\)
Hãy chỉ ra các kết quả đúng trong các kết quả sau :
a) \(\int\limits^1_0x^n\left(1-x\right)^mdx=\int\limits^1_0x^m\left(1-x\right)^ndx;m,n\in\mathbb{N}^{\circledast}\)
b) \(\int\limits^1_{-1}\dfrac{t^2}{e^t+1}dx=\int\limits^1_0t^2dt\)
c) \(\int\limits^1_0\sin^3x\cos xdx=\int\limits^1_0t^3dt\)
\(\int\limits^{lne}_0log_2e^x.7^xdx\)
\(\int\limits^{\dfrac{\pi}{2}}_{\dfrac{\pi}{3}}\dfrac{1+sinx}{1+cosx}e^xdx\)
Ok bat ong doi lau roi
\(\int\dfrac{1+\sin x}{1+\cos x}e^xdx=\int\dfrac{e^xdx}{1+\cos x}+\int\dfrac{e^x\sin x}{1+\cos x}dx\)
\(I_1=\int\dfrac{e^xdx}{1+\cos x}\)
\(I_2=\int\dfrac{e^x\sin x}{1+\cos x}dx\)
\(\left\{{}\begin{matrix}u=\dfrac{\sin x}{1+\cos x}\\dv=e^xdx\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}du=\dfrac{\cos x\left(1+\cos x\right)+\sin^2x}{\left(1+\cos x\right)^2}dx=\dfrac{dx}{1+\cos x}\\v=e^x\end{matrix}\right.\)
\(\Rightarrow I_2=\dfrac{e^x.\sin x}{1+\cos x}-\int\dfrac{e^xdx}{1+\cos x}=\dfrac{e^x\sin x}{1+\cos x}-I_1\)
\(\Rightarrow I=\dfrac{e^x\sin x}{1+\cos x}\)
P/s: Done, ông thay cận vô nhé :)
\(\int\limits^{\frac{\pi}{2}}_0\sin^4x.\cos xdx\)
Tính tích phân :
\(\int\limits^e_1x^2\ln xdx\)
Đặt \(u=\ln x\rightarrow du=\frac{dx}{x};dv=\int x^2dx\rightarrow v=\frac{1}{3}x^3\)
Do đó : \(I=\frac{1}{3}x^3\ln x|^e_1-\frac{1}{3}\int\limits^e_1x^2dx=\frac{e^3}{3}-\frac{1}{3}x^3|^e_1=\frac{2e^3+1}{9}\)
Tính :
a) \(\int\limits^2_{-1}\left(5x^2-x+e^{0,5x}\right)dx\)
b) \(\int\limits^2_{0,5}\left(2\sqrt{x}+\dfrac{3}{x^2}+\cos x\right)dx\)
c) \(\int\limits^2_1\dfrac{dx}{\sqrt{2x+3}}\) (đặt \(t=\sqrt{2x+3}\) )
d) \(\int\limits^2_1\sqrt[3]{3x^3+4}x^2dx\) (đặt \(t=\sqrt[3]{3x^3+4}\) )
e) \(\int\limits^2_{-2}\left(x-2\right)\left|x\right|dx\)
g) \(\int\limits^0_1x\cos xdx\)
h) \(\int\limits^{\dfrac{\pi}{2}}_{\dfrac{\pi}{6}}\dfrac{1+\sin2x+\cos2x}{\sin x+\cos x}dx\)
i) \(\int\limits^{\dfrac{\pi}{2}}_0e^x\sin xdx\)
k) \(\int\limits^e_1x^2\ln^2xdx\)
\(\int\limits^{\frac{\pi}{4}}_0\left(tan^2x+tanx\right).e^xdx\)
Tính tích phân : \(I=\int\limits^1_0\left(x-e^{2x}\right)xdx\)
\(I=\int\limits^1_0\left(x+e^{2x}\right)xdx=\int\limits^1_0x^2dx+\int\limits^1_0xe^{2x}dx=I_1+I_2\)
\(I_1=\int\limits^1_0x^2dx=\frac{x^3}{3}|^1_0=\frac{1}{3}\)
Đặt \(\begin{cases}dv=e^{2x}dx\\u=x\end{cases}\) ta có \(\begin{cases}v=\frac{e^{2x}}{2}\\du=dx\end{cases}\)
\(I_2=\frac{xe^{2x}}{2}|^1_0-\int\limits^1_0\frac{e^{2x}}{2}dx=\left(\frac{xe^{2x}}{2}-\frac{e^{2x}}{4}\right)|^1_0=\frac{e^2+1}{4}\)
\(I=I_1+I_2=\frac{e^2+1}{4}+\frac{1}{3}=\frac{3e^2+7}{12}\)