Gauss-Laguerre quadrature

For the weight $e^{-x}$ on $[0,\infty )$, use the zeros of a degree-$n$ Laguerre polynomial as quadrature nodes. Divide a polynomial of degree at most $2n-1$ by that polynomial. The quotient term integrates to zero by orthogonality and vanishes at every node; interpolation of the remainder proves exactness. The two-node rule has nodes $2\pm \sqrt{2}$ and corresponding weights $(2\pm \sqrt{2})/4$, with the larger weight at the smaller node.