Wrong syntax construction altogether. You have entered into php by using <? and ?>, so you need to echo the html
<?
echo '<FORM ACTION="PDC_Hotline_Submitted.php?useripaddy='.$user_ip_addy.'&dateopened='.$date_opened.'" METHOD="POST" NAME="PDC_Hotline" onSubmit="return formValidation(this);">';
?>
Also, when using the single-quote syntax for php strings you do not have to escape the embedded html double-quotes.
Also, the onsubmit function call needs a javascript statement terminator ';'