Parabola graph of -2x^2-8x-10

						var board = JXG.JSXGraph.initBoard('box1', {
boundingbox: [-10, 10, 5, -20],showcopyright: false,showNavigation: false,axis: true,defaultAxes: {
    y: { ticks: {majorHeight: 5 } },
	x: { ticks: {majorHeight: 5 } },
  }, 
});
 
board.create('functiongraph', [function(x){ return -2*x*x-8*x-10; },-10, 10],{strokeColor: "blue",strokewidth:2})