Answer: B.
Step-by-step explanation:
When there is an exponent of another exponent, you can multiply them together:
As such, the expression in the image can be simplified to
[tex]r^{-7*6}[/tex], or r ^ -42.
Negative exponents can also be represented by positive exponents in the denominator of a fraction.
For instance, [tex]x^{-2}[/tex] can be rewritten as [tex]\frac{1}{x^2}[/tex].
The correct answer is [tex]\frac{1}{r^{42} }[/tex].
