forms of same id in while loop - how to post formdata of user submitted form to php with jquery ajax : I have a while loop wich creates forms like:

    <?php
		     	$i = 1;
			while($i<10){   
			 
		      ?>
		<form id="update">
		      <tr> 
		      <th scope="row"><?php echo $i;?></th>
		      <td></td>
		      <td></td>
		      <td></td>
		      <td><input type="text" maxlength="5" class ="input-xs valid" name="plus" value=""></td>
		      <td><input type="submit" name="submit" class="btn btn-info btn-sm" value="Update"></td>
		      <td><input class="input-sm slip" name="slip" value="" disabled/></td>
		      <td></td>
		      </tr> 
			 </form>
		      <?php $i++; }  ?>
I want to post the formdata of user submitted form with jquery ajax.