Evaluate ∫xe−x dx\int xe^{-x}\,dx∫xe−xdx.
−e−x(x+1)+C-e^{-x}(x+1) + C−e−x(x+1)+C
−e−x(x−1)+C-e^{-x}(x-1) + C−e−x(x−1)+C
−xe−x+C-xe^{-x} + C−xe−x+C
e−x(x+1)+Ce^{-x}(x+1) + Ce−x(x+1)+C