; Problem: There are two roots of the quadratic equation (or at least
; there usually are. How do I get them both?
; (1) Does Scheme provide a way to represent more than one value?
; Yes, put them in a list
(define roots
(lambda (a b c)
(list
(/ (+ (- b) (sqrt (- (* b b) (* 4 a c))))
(* 2 a))
(/ (- (- b) (sqrt (- (* b b) (* 4 a c))))
(* 2 a)))))