So I understand to simplify this:
$$ \frac{\frac{-3}{2t^4}}{|\frac{1}{2t^3}|\sqrt{\frac{1}{4t^6} - 1}} $$
I can just multiply
$$ \frac{\frac{-3}{2t^4}}{|\frac{1}{2t^3}|\sqrt{\frac{1}{4t^6} - 1}} \cdot\frac{2t^4}{2t^4} $$
and get
$$ \frac{-3}{t\sqrt{\frac{1}{4t^6} - 1}} $$
But how do you simplify further getting rid of the complex fraction inside the radical?
$\frac{\frac{-3}{2t^4}}{|\frac{1}{2t^3}|\sqrt{\frac{1}{4t^6} - 1}} \frac{\sqrt {4t^6}}{\sqrt{4t^6}}$ first step will be to get rid of the fraction inside the radical. Note that ${\sqrt{4t^6}} = |2t^3|$
$\frac{\frac{-3}{2t^4}|2t^3|}{|\frac{1}{2t^3}|\sqrt{1 - 4t^6}} \frac{\sqrt {1-4t^6}}{\sqrt{1-4t^6}}$ Then we get the radical outside of the numerator.
$ \frac{\frac{-3}{2t^4}|2t^3|\sqrt {1-4t^6}}{|\frac{1}{2t^3}|(1 - 4t^6)} \frac{|2t^3|}{|2t^3|}$ Now I am taking on what you did in the first step. I think it is best to attack the messiest parts first.
$ \frac{\frac{-3}{2t^4}(4t^6)\sqrt {1-4t^6}}{(1 - 4t^6)}\\ \frac{-6t^2\sqrt {1-4t^6}}{(1 - 4t^6)}$