solving equations

[dcgirl]

how do i solve
4th root of 16^8y^-4

 

[pka]

\(\displaystyle \L
\sqrt[4]{{16^8 y^{ - 4} }} = 16^2 \left| {y^{ - 1} } \right| = \frac{{256}}{{|y|}}\), note that the absolute value is necessary because of domain issues.

 

[dcgirl]

how did u get the 16^2

 

[pka]

Come on! You try to figure it out.
Where did −1 come from?

 

[dcgirl]

but the 4th root of 16 isnt 16

 

[pka]

\(\displaystyle \L
\sqrt[4]{{16^8 }} = \sqrt[4]{{\left( {2^4 } \right)^8 }} = \sqrt[4]{{\left( {2^{32} } \right)}} = 2^8 = \left( {2^4 } \right)^2 = 16^2\)