Question

how do you simplify (6y)^-2

Answer 1

A negative exponent means you can flip whatever the exponent is attached to upside down to make it positive. So for example:
\[(2x)^{-3}=\frac{ 1 }{ (2x)^{3} }\]
After that, just know
\[(6y)^{2}=6^{2}y ^{2}\]