Divide and simplify. Assume that all variables are positive.

Divide and simplify. Assume that all variables are positive.  $$\frac{\sqrt{180x^5}}{\sqrt{5x^3}}$$  

Multiply and simplify. Assume that all variables are positive.

Multiply and simplify. Assume that all variables are positive. $$\sqrt{7x^5}\cdot\sqrt{42xy^9}$$  

1. Multiply & Simplify.

$$\left(2-\sqrt{3}\right)\left(4+\sqrt{2}\right)$$  

Multiply and simplify $$\left(6+\sqrt{2}\right)\left(6-\sqrt{2}\right)$$  

Simplify $$\left(5\ -\sqrt{11}\right)\left(5\ +\sqrt{11}\right)$$