I'm not entirely sure whether this is a suitable problem to ask. However, in trying to solve an index problem, I have been getting stuck in the same place for a while.
The question is:
$$(9a^3 b^{-4})^{1/2} \times 2(a^{1/2}b^{−2})^{−2}$$
I know that the answer is
$$6a^{1/2} \times b^{2}$$
But I'm unsure exactly how to get there. I know I must start by expanding; however, I then get stuck.