I'm assuming that you're asking about
![\sqrt[5]{4x^2}\cdot\sqrt[5]{4x^2}](https://img.qammunity.org/2019/formulas/mathematics/middle-school/nwo7f874ndnjl185clmcblt1r2uswqj3uu.png)
If this is the case, you need to use the following rule:
![\sqrt[a]{b}\cdot\sqrt[a]{c} = \sqrt[a]{bc}](https://img.qammunity.org/2019/formulas/mathematics/middle-school/g5meoe0fxbudwpx1nae7ge75urdwck1d1j.png)
In other words, if the roots have the same order, the multiplication of the roots is the same thing as the root of the product of their content.
So, we have
![\sqrt[5]{4x^2}\cdot\sqrt[5]{4x^2} = \sqrt[5]{4x^2 \cdot 4x^2} = \sqrt[5]{16x^4}](https://img.qammunity.org/2019/formulas/mathematics/middle-school/429933aglp9g02ivzhaqghcptmu4sus33b.png)