Always look at the prime factorization of the numbers under the radical signs to know what can be moved out from under the radical sign...
√8+3√2+√32 so
√(2*2*2)+3√2+√(2*2*2*2*2) so upon removing the perfects squares...
2√2+3√2+4√2 which is
(2+3+4)√2
9√2