Chapter 5 - Section 5.7 - Negative Exponents and Scientific Notation - Exercise Set - Page 409: 64

$x^{7}$

Using the laws of exponents, the given expression, $ (x^4)^3\cdot x^{-5} ,$ simplifies to \begin{array}{l}\require{cancel} x^{4(3)}\cdot x^{-5} \\\\= x^{12}\cdot x^{-5} \\\\= x^{12+(-5)} \\\\= x^{12-5} \\\\= x^{7} .\end{array}