Magnification with falloff

I am trying to make an array of thumbnails that is magnified as you rollover them. I’ve got it to array, but it only magnifies in the x or y direction. I think, if I can get this chunk of code to include mousex, it would work:

			if(_root["holder"+i]._y > mousey){
				_root["holder"+i].scalefc = mousey / _root["holder"+i]._y;
				_root["holder"+i].scalefc = (_root.stageHeight-mousey) / (_root.stageHeight-_root["holder"+i]._y);

Please, please help!