function calculate(){
	var a = document.getElementById("a").value;
	var b = document.getElementById("b").value;
	var c = document.getElementById("c").value;
	var x1, x2, sq, dis;
	if (a != "" && b != "" && c != "") {
        a = parseFloat(a);
		b = parseFloat(b);
		c = parseFloat(c);
        dis = ((b*b)-(4*a*c));
        if (dis < 0){
            sq = Math.sqrt(Math.abs((b*b)-(4*a*c)));
            x1 = Math.round((-1 * b)/(2*a)*1000)/1000 + " + " + Math.round((sq)/(2*a)*1000)/1000 + "i";
            x2 = Math.round((-1 * b)/(2*a)*1000)/1000 + " - " + Math.round((sq)/(2*a)*1000)/1000 + "i";
        } else {
            sq = Math.sqrt((b*b)-(4*a*c));
            x1 = ((-1 * b) + sq)/(2*a);
            x2 = ((-1 * b) - sq)/(2*a);
        }
        
		document.getElementById("x<sub>1</sub>").innerHTML = "x<sub>1</sub>: " + x1;
		document.getElementById("x<sub>2</sub>").innerHTML = "x<sub>2</sub>: " + x2;
	}
}