## Introductory Algebra for College Students (7th Edition)

$70x^{9}$
Mulyiplying the constants and multiplying the variables, the product of the given expression, $(-10x^4)(-7x^5) ,$ is \begin{array}{l}\require{cancel} -10(-7)x^{4+5} \\\\= 70x^{9} .\end{array}