9√33

9√11

8√11

They aren't like terms

$\sqrt{3}\ and\ \sqrt{9}$

$\sqrt{8}\ and\ \sqrt{2}$

$\sqrt{8}\ and\ \sqrt{4}$

$\sqrt{8}\ and\ \sqrt{3}$

 $34\sqrt{5}$  

 $\sqrt{170}$  

 $8\sqrt{5}$  

can't add

 $2+4\sqrt{7}$  

 $2+4\sqrt{14}$  

 $2-12\sqrt{7}$  

 $6$  

 $9\sqrt{10}$  

 $-\sqrt{10}$  

 $9\sqrt{100}$  

 $5\sqrt{10}$