MathJax Equation AngularJS

HTML

<script src="http://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML&amp;dummy=.js"></script>
<div ng-controller="MyCtrl">
    <button ng-click="Update()">Update</button>
    {{Label}} <span id="mathElement">{{Expression}}</span>
</div>

JavaScript

var myApp = angular.module('myApp',[]);

//myApp.directive('myDirective', function() {});
//myApp.factory('myService', function() {});

function MyCtrl($scope, $element) {
    $scope.Update = function() {
        $scope.Expression = '\\frac{9}{4} \\div \\frac{1}{6}';
        $scope.Label = 'Updated Expression:'
        var math = MathJax.Hub.getAllJax("mathElement")[0];
        math.Text('\\frac{4}{4} \\div \\frac{2}{6}');
    }
    $scope.Expression = '\\( \\frac{5}{4} \\div \\frac{1}{6} \\)'
    $scope.Label = 'Original Expression:'
}