How to get the second expression from the first one?

Question

I have the following expression

$(I_2)^{\frac{1}{2}}(1 - \displaystyle\frac{b I_3}{(I_2)^{3/2}})^{\frac{1}{3}}$

for which $I_2$ is always positive (the only constraint that I have).

I would like to know how can I reach the following expression:

$((I_2)^\frac{3}{2} - b I_3)^{\frac{1}{3}}$

I have found the above equality in a scientific paper.

Thanks in advance

Answer 1

It is $$\frac{I_2^{1/2}\left(I_2^{3/2}-bI_3\right)^{1/3}}{\left(I_2^{3/2}\right)^{1/3}}$$ and you can cancel $I_2$