; 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)))))