Chapter 5 - Section 5.2 - Multiplying Polynomials - Exercise Set - Page 359: 54

$-18x^4+12x^3+42x^2$

Using $a(b+c)=ab+ac$ or the Distributive Property, the given expression, $ -6x^2(3x^2-2x-7) ,$ is equivalent to \begin{array}{l}\require{cancel} -6x^2(3x^2)-6x^2(-2x)-6x^2(-7) \\\\= -18x^4+12x^3+42x^2 .\end{array}