UV আকারের (Integration by parts)

01lnxdx \int_{0}^{1} \ln x d x

Solve:

lnxdx=lnxdx{ddx(lnx)dx}dx=xlnx1xxdx=xlnxdx=xlnxx+c=x(lnx1)+c01lnxdx=[x(lnx1)]01=(1.ln11)0=1( Ans: ) \begin{aligned} \therefore \quad & \int \ln x d x \\ = & \ln x \int d x-\int\left\{\frac{d}{d x}(\ln x) \int d x\right\} d x \\ = & x \ln x-\int \frac{1}{x} x d x=x \ln x-\int d x \\ = & x \ln x-x+c=x(\ln x-1)+c \\ \therefore \quad & \int_{0}^{1} \ln x d x=[x(\ln x-1)]_{0}^{1} \\ & =(1 . \ln 1-1)-0=-1(\text { Ans: }) \end{aligned}

UV আকারের (Integration by parts) টপিকের ওপরে পরীক্ষা দাও