The last expression is wrong: it must have x in the numerator. No wonder, since you expanded the product in the numerator in a terrible way: didn't you pay attention to the fact that you had an expression of the very easy form difference of squares?

Fix this, and then multiply the whole expression by so that you'll be able to divide each term in numerator and denominator by x (and get the x into the square root as ...!)

Tonio