Hello! In article <39618db4$1_1@spamkiller.newsfeeds.com>, Janos Blazi <jblazi@vipsurf.de> wrote: >(/ (+ (- b) (sqrt ( - (* b b) (* 4 (* a c))))) (* 2 a)) Besides from changing reader syntax: (let* ((discriminant (- (* b b) (* 4 a c))) (numerator (- (sqrt discriminant) b)) (denominator (* 2 a))) (/ numerator denominator)) >[...] Regards, Hannah.