Yes, #id selectors combined with a multiple selector (comma) is perfectly valid in both jQuery and CSS.
However, for your example, since <script> comes before the elements, you need a document.ready handler, so it waits until the elements are in the DOM to go looking for them, like this:
<script>
$(function() {
$("#segement1,#segement2,#segement3").hide()
});
</script>
<div id="segement1"></div>
<div id="segement2"></div>
<div id="segement3"></div>