Chapter 5 - Section 5.2 - More Work with Exponents and Scientific Notation - Exercise Set - Page 268: 51

$\dfrac{1}{x^{30}b^{6}c^{6}}$

Using laws of exponents, the given expression simplifies to \begin{align*} & x^6\left( x^6bc \right)^{-6} \\\\&= x^6\left( x^{6(-6)}b^{-6}c^{-6} \right) \\\\&= x^6\left( x^{-36}b^{-6}c^{-6} \right) \\\\&= x^{6+(-36)}b^{-6}c^{-6} \\\\&= x^{-30}b^{-6}c^{-6} \\\\&= \dfrac{1}{x^{30}b^{6}c^{6}} .\end{align*}