Answer
$2\sqrt7-4$
Work Step by Step
$\frac{6}{\sqrt7+2}\longrightarrow$ multiply numerator and denominator by conjugate of denominator
=$\frac{6}{\sqrt7+2}\times\frac{\sqrt7-2}{\sqrt7-2}\longrightarrow$ multiply
=$\frac{6\sqrt7-12}{7-4}\longrightarrow$ simplify
=$\frac{6\sqrt7-12}{3}\longrightarrow$ divide by 3
=$2\sqrt7-4$
