Answer:
[tex]\frac{1}{r^4^2}[/tex] (option B)
Step-by-step explanation:
[tex]\left(a^b\right)^c=a^{bc},[/tex]
So, we need to first multiple -7 × 6 (= -42)
our new value is [tex]r^{-42\\}[/tex]
[tex]\:a^{-b}=\frac{1}{a^b}[/tex]
So, we simplify [tex]r^{-42\\}[/tex] to [tex]\frac{1}{r^4^2}[/tex]
