Since the expression is > 0, hence, the x values are above the x -axis, right? And since the graph is a "smiling" graph, x > 4 or x < -1. That's how I got it.
You made a mistake here . You CANNOT multiply x-2 with x because u don know whether x is positive or negative . If its positive , the sign is not affected but if its negative , the sign will be affected.