1. ## stumped! rules for radicals/roots

I'm on the last problem of a practice test and stuck i followed the sample problem in the book but isn't clicking....pardon the attachment not sure how to post symbols and such.

2. Originally Posted by roger90
I'm on the last problem of a practice test and stuck i followed the sample problem in the book but isn't clicking....pardon the attachment not sure how to post symbols and such.

1. Transform the terms into powers:

$\sqrt[4]{32xy^4} - y \cdot \sqrt[4]{162 xy^4} = \left(2 \cdot 2^4 \cdot x \cdot y^4 \right)^{\frac14} - y \cdot \left(2 \cdot 3^4 \cdot x \right)^{\frac14}$

2. Factor out $(2x)^{\frac14}$ and collect like terms in the bracket.

3. You should come out with $-y(2x)^{\frac14}$

3. Thanks for the help.