anchor.diff:                  </div>
                   <div class="form-group  col-3">
                               <label for="selectPeriodo">Período da Taxa</label>
  -                            <select id="selectPeriodo" class="form-control" id="exampleSelect1">
  +                            <select onchange="myFunction()" id="selectPeriodo" class="form-control" id="exampleSelect1">
                                   <option>Mensal</option>
                                   <option>Anual</option>
                               </select>
  
positive.code:              <table class="table table-hover" style="border-color:red;">
                   <thead>
                  <tr>
                      <th>Período(meses)</th>
                      <th>Prestação</th>
                      <th>Juros</th>
                      <th>Amortização</th>
  
negative.code:     
  
      <%@include file="WEB-INF/jspf/footer.jspf" %>
      <script>
      function myFunction() {
          var x = document.getElementById("selectPeriodo").value;
          document.getElementById("demo").innerHTML = "Período("+x+")";
      }
      </script>
  
      </body>
  