You can
put this solution on YOUR website!You didn't do anything wrong. With even roots, you can get extraneous solutions (false solutions) in which you did everything right and got a solution which doesn't check out. That's why you always have to check your solutions in even root equations, rational equations and log equations. I think you probably typed in your steps wrong, but I got x=100 also. And your right, it doesn't check, therefore, this equation has no solution.
Happy Calculating!!!