Question

What is the radical part of both 3 squared squareroot of 54 and 3squared squareroot of 128 when the expressions are simplified?

Answer 1

Assuming you mean 3^2·√54 and 3^2·√128 (and the "radical part" is the simplified part under the square root):

9√54 = 9·√(9·6) = 9·3√6 = 27√6 → radical part: √6 (inside: 6)

9√128 = 9·√(64·2) = 9·8√2 = 72√2 → radical part: √2 (inside: 2)

(If you instead meant 3·√54 and 3·√128, the radical parts are the same: √6 and √2.)