If $\frac{1}{1-2 x+x^2}=1+a_1 x+a_2 x^2+\ldots$ then $\mathrm{a}_{\mathrm{f}}=$

Question

Professor PC Thomas Classes · Answer

$1+\mathrm{a}_1 \mathrm{x}+\mathrm{a}_2 \mathrm{x}^2+\ldots=(1-\mathrm{x})^{-2}$ $ \  \begin{aligned} & A_t=	ext { coefficient of } \ & x^r=r+1 \end{aligned} $