Negative radical exponent simplification

Hi,

I am dealing with the following problem and am unsure whether

I solved it right:

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(16xy)^(1/4) (-8x^2z^3)^(-1/3)

--------------------------------

(25^-1 x^2 yz)^(-1/2)

2(xy)^(1/4) (-8x^2z^3)^(-1/3)

= ------------------------------

((25^-1 x^2 yz)^-1)^(1/2))

2(xy)^(1/4) (-8x^2z^3)^(-1/3)

= --------------------------------

(25x^-2y^-1z^-1)^(1/2)

2(xy)^(1/4)

= ---------------------------------------------

5(x^-2y^-1z^-1)^(1/2) (-8x^2z^3)^(1/3)

= 2(xy)^(1/4)

---------------------------------

5(x^-2y^-1z^-1)^(1/2) -2z(x^2)^(1/3)

===================================

Thanks for the help,

Alex