√20x *√5x3 - We can involve the action under the square root, because we have a multiplication of two square root elements.
[tex] \sqrt{20x*5x^{3}} = \sqrt{20*5 x^{4} } = \sqrt{100} *x^{2} = 10x^{2}[/tex]
We are using the fact, that the multiplication of the square roots is alternating.
