function checnum(as)
{
	//alert("*********");
	var a = as.value;
	for(var x=0; x<a.length; x++)
	{
		var ff = a[x];
	
		if(isNaN(ff) && ff != "/" && ff != "-")
		{
			alert("Enter a proper value");
			break;
		}
	}
}

function two()
{
	var x1 = document.first.x1.value;
	var y1 = document.first.y1.value;
	var x2 = document.first.x2.value;
	var y2 = document.first.y2.value;
	var a = y1 -(y2);
	var b = -(x1) + parseInt(x2);
	var c = -(x1*y1) + (x1*y2) + (x1*y1) - (x2*y1);
	a = a + "x";
	b = b + "y";
	if(a>0)
		a="+ " + a;
	if(b>0)
		b="+ " + b;
	if(c>0)
		c="+ " + c;
	document.first.r1.value = a + b + c;
}
	
function color(test)
{

	for(var j=2; j<10; j++)
	{
		var myI=document.getElementsByTagName("input").item(j);
		//myI.setAttribute("style",ch);
		myI.style.backgroundColor=test;
	}
}

function color1(test)
{
var myI=document.getElementsByTagName("table").item(0);
//myI.setAttribute("style",ch);
myI.style.backgroundColor=test;
}