Question

ah

Answer 1

\[\frac{9}{7-3\sqrt3}\] multiply top and bottom by the conjugate of the denominator, which is \(7+3\sqrt3\)

Answer 2

this works because \((a+b)(a-b)=a^2-b^2\) and so
\[(7-3\sqrt3)(7+3\sqrt3)=7^2-(3\sqrt3)^2=49-27=22\]

Answer 3

so you get
\[\frac{9(7+3\sqrt3)}{22}\]