@Override
   public String convertToGeneralForm(String monom) {
      if (!monom.contains("x")) {
         monom = monom + "x0";
      }
      if (monom.contains("x") && (monom.length() == monom.indexOf("x") + 1)) {
         monom = monom + "1";
      }
      if (monom.indexOf("x") == 0) {
         monom = "1" + monom;
      }
      if ((monom.indexOf("x") == 1) && (monom.indexOf("-") == 0)) {
         monom = monom.substring(0, 1) + "1" + monom.substring(1, monom.length());
      }
      return monom;
   }