ACCESO AL SISTEMA PHP

FORMULARIO

                                                     
                                                       <h1> acceso al sistema </h1>
                                                      <form action="formulario6.php"method="post">
                                                       usuario<input type="text" name="user" /><br/>
                                                      clave<input type="password"name="pass" /><br/>
                                                      <input type="submit"valve="ingrese el sistema"/><br/>
                                                      </form>
    

                                                                    
                                                                   <h1> autollamado </h1>
 
                                                     <?php
                                                     $numeros = array (1,2);
                                                     for ($x = 2 ; $x < = 19 ; x++){
                                                     $numeros[x]=$numeros[x-2]+$numeros[$x-1];
                                                     }
                                                     echo "<p> posicion 19:$numeros[19]</p>";
                                                     print_r($numeros);
                                                     ?>

                                                                   <h1>validando datos </h1>
                                                    <?php
                                                    if($_post["usuario"]== "agustin"&& $_post["contrasena"]=="examen"){
                                                    $usuario = $_post["usuario"];
                                                    echo "hola $usuario<br/> datos correctos";
                                                    }else{
                                                    echo "los datos ingresados son incorrectos";
                                                    }

                             
                                                                 <h1> datos de acceso </h1>
                                                     <from action = "examen2.php" method = "post">
                                                     usuario<input type = "text" name = "usuario" /> <br/>
                                                     contrase&ntilde;a <input type = "password" name = "contrasena"/>
                                                     <input type = "submit" valve ="ingresar"/>
                                                     </from>

                                                    <p><a href="examen1.php">volver</a></p>