The Multiplication Parabola

The underlying JavaScript code

var brd = JXG.JSXGraph.initBoard('box', {axis:true, boundingbox: [-4, 11, 4, -1]});
var f = brd.create('functiongraph',[function(x){return x*x;}],{strokeColor:'black',highlightStrokeColor:'black'});
var a = brd.create('glider',[-2,4,f]);
var b = brd.create('glider',[3,9,f]);
var g = brd.create('line',[a,b],{straightFirst:false,straightLast:false});
var p = brd.create('point',[function(){return 0.0;},function(){return -a.X()*b.X();}],{fixed:true});
var t = brd.create('text',[-1.5,9,function(){ return '-X(A)*X(B) = '+a.X().toFixed(2)+'*'+b.X().toFixed(2)+' = '+(-a.X()*b.X()).toFixed(2)+' = Y(C)';}]);