Jquery datepicker control is not working inside child control of master page

Jquery datepicker is working in normal webpage but not with master page concept.It's throwing error saying "0x800a01b6 - JavaScript runtime error: Object doesn't support property or method 'datepicker'".

Tried following approaches but no luck.

1st Approach:

$('#<%= datepicker.ClientID %>').datepicker();

2nd Approach:

$(".datepicker").datepicker();

3rd Approach: Placed jquery script files in master page and datepicker code between script tag inside content placeholder like below

<script type="text/javascript">
$('#<%= datepicker.ClientID %>').datepicker();
</script>

Please suggest other approaches to make it work.