Answer
$-\frac{1}{343}$
Work Step by Step
The given expression is
$=-7\cdot (-7)^{-4}$
$=(-7)^1\cdot (-7)^{-4}$
Use $a^n\cdot b^m=a^{n+ m}$.
$=(-7)^{1-4}$
Simplify.
$=(-7)^{-3}$
Use $a^{-n}=\frac{1}{a^n}$.
$=\frac{1}{(-7)^{3}}$
Use $(-7)^3=-343$.
$=-\frac{1}{343}$.
