can't assign value's to variable
<p>i tries to run this code and i got a http 500 error so i comment out line by line and i saw that the problem arise when i try to assign the values to the variable's i even tried to assign just a simple string and i got error can anyone help me </p>

<pre><code>require 'connect_to_database.php';

    $user_id = $_REQUEST['user_id'];

    $select_query = "SELECT * FROM users WHERE user_id = " . $user_id;

    $result = mysql_query($select_query);

    if ($result)  {
    $row = mysql_fetch_array($result);
    $first_name = hello;
    $last_name = $row['last_name'];
    $bio = $row['bio'];
    $email = $row['email'];
    $faebook_url = $row['facebook_url'];
    $twitter_url = $row['twitter_handle'];
    $user_image = "../../images/missing_user.png;"

    } else {
    die("Error locating user with ID {$user_id}");
    } 
    ?&gt;

    &lt;html lang="en"&gt;
    &lt;head&gt;
    &lt;meta charset="utf-8" /&gt;
    &lt;title&gt;&lt;/title&gt;
    &lt;link href="../../css/phpMM.css" rel="stylesheet" type="text/css"&gt;
    &lt;/head&gt;
    &lt;body&gt;
    &lt;div id="header"&gt;&lt;h1&gt;The Missing Manual&lt;/h1&gt;&lt;/div&gt;
    &lt;div id="example"&gt;User profile&lt;/div&gt;
    &lt;div id="content"&gt;
    &lt;div class="user_profile"&gt;
    &lt;h1&gt;&lt;?php echo "{$first_name} {$last_name}"; ?&gt;&lt;/h1&gt;
    &lt;p&gt;&lt;?php  echo $bio; ?&gt;&lt;/p&gt;
    &lt;p class="contact_info"&gt;Get in touch  &lt;?php echo $first_name; ?&gt;:&lt;/p&gt; 
           &lt;ul&gt;
    &lt;li&gt;...by emailing them at &lt;a href="&lt;?php echo $email; ?&gt;"&gt;  
    &lt;?php echo $email; ?&gt;&lt;/a&gt;&lt;/li&gt;
    &lt;li&gt;...by &lt;a href="&lt;?php echo $faebook_url; ?&gt;"&gt;
     checking them out on  facebook&lt;/a&gt;&lt;/li&gt;
              &lt;li&gt;...by &lt;a href="&lt;?php echo $twitter_url; ?&gt;"&gt;
     following them on twitter&lt;/a&gt;&lt;/li&gt;
           &lt;/ul&gt;
       &lt;/div&gt;
      &lt;/div&gt;
      &lt;div id="footer"&gt;&lt;/div&gt;
     &lt;/body&gt;
    &lt;/html&gt;
</code></pre>