2_87.scm

(define (install-polynomial-package)
  (define (zero-poly? p)
    (define (zero-termlist? terms)
      (or (empty-termlist? terms)
        (and (=zero? (coeff (first-term terms)))
             (zero-termlist? (rest-terms terms)))))
    (zero-termlist? (term-list p)))
  (put '=zero? '(polynomial) (lambda (p) (zero-poly? p)))

(define (=zero? x) (apply-generic '=zero? x))