Chapter 5 Polynomials and Polynomial Functions - 5.1 Use Properties of Exponents - 5.1 Exercises - Skill Practice - Page 334: 43

$x^{11} y^5 z^{-3}$

Here, we have $x^{15} y^{12}z^{8}=a \times x^{4} y^{7} z^{11}$ Now, $a= \dfrac{ x^{15} y^{12}z^{8}}{x^{4} y^{7} z^{11}}$ This gives: $a=x^{15-4} \times y^{12-7} \times z^{8-11}=x^{11} y^5 z^{-3}$