Tích phân \(I=\displaystyle\int\limits_{0}^{1}x\cdot2^x\mathrm{\,d}x\) bằng
\(\dfrac{2\ln2-1}{\ln^22}\) | |
\(\dfrac{2\ln2-1}{\ln2}\) | |
\(\dfrac{2\ln2+1}{\ln^22}\) | |
\(\dfrac{2\ln2+1}{\ln2}\) |
Chọn phương án A.
Đặt \(\begin{cases}
u=x\\ v'=2^x
\end{cases}\Rightarrow\begin{cases}
u'=1\\ v=\dfrac{2^x}{\ln2}
\end{cases}\)
Khi đó $$\begin{aligned}I=&\dfrac{x\cdot2^x}{\ln2}\bigg|_0^1-\displaystyle\int\limits_{0}^{1}\dfrac{2^x}{\ln2}\mathrm{\,d}x\\ =&\dfrac{2}{\ln2}-\dfrac{2^x}{\ln^22}\bigg|_0^1=\dfrac{2\ln2-1}{\ln^22}.\end{aligned}$$