0. Review of College Algebra

Rationalize the denominator. 

$-\frac{5}{2\sqrt7}$

Rationalize the denominator.

$\frac{6+\sqrt{x}}{-\sqrt{x}}$

Rationalize the denominator and simplify the radical expression.

$\frac{\sqrt7}{5-\sqrt6}$

Rationalize the denominator and simplify the radical expression.

$\frac{2-\sqrt3}{2+\sqrt3}$