(36a6b4)3/2

It is easier to take the square roots first if you have perfect squares

$$\\(36a^6b^4)^{3/2}\\\\ =36^{3/2}(a^6)^{3/2}(b^4)^{3/2}\\\\ =36^{3/2}\;\;a^{6*3/2}\;\;b^{4*3/2}\\\\ =(36^{1/2})^3\;\;a^{9}\;\;b^{6}\\\\ =(\sqrt{36})^3\;\;a^{9}\;\;b^{6}\\\\ =(6)^3\;\;a^{9}\;\;b^{6}\\\\ =216\;a^{9}\;b^{6}\\\\$$

First, cube all the terms like 36^3, a^6^3, etc.

Then, take the square root of each one.