(define (wielom e lx)
  (if (not (pair? e)) ; czy wyrazenie e jest wyrazeniem prostym
      (if (number? e)
          #t
          (if (member e lx)
              #t
              #f))
      (if (or (equal? (car e) '+) (equal? (car e) '-) (equal? (car e) '*))
          (and (wielom (cadr e) lx) (wielom (caddr e) lx))
          (if (equal? (car e) '/)
              (and (wielom (cadr e) lx) (nzero (caddr e)))
              (if (equal? (car e) '^)
                  (and (wielom (cadr e) lx) (nat (caddr e)))
                  #f)))))