A very very long base element x + ( 1 + x 2 ) - 1 1 + λ 2 ( 1 x ) n = lim x + x n ( 1 + x 2 ) 1 1 + λ 2 = lim x + [ x n ( 1 + λ 2 ) 1 + x 2 ] 1 1 + λ 2