Answer:
D. (2^6)^-5
Step-by-step explanation:
The exponent rules are ...
[tex]a^ba^c=a^{b+c}\\\\(a^b)^c=a^{bc}[/tex]
Exponents are multiplied when an exponential expression is raised to a power.
A.
[tex]\left(\dfrac{1}{5}\right)^2\left(\dfrac{1}{5}\right)^6=\left(\dfrac{1}{5}\right)^{2+6}=\left(\dfrac{1}{5}\right)^8 \quad\text{exponents added}[/tex]
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B.
[tex]\dfrac{9^3}{9^4}=(9^3)(9^{-4})=9^{3-4}=9^{-1} \quad\text{exponents added}[/tex]
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C.
[tex](7^3)(7^{8})=7^{3+8}=7^{11} \quad\text{exponents added}[/tex]
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D.
[tex](2^6)^{-5}=2^{6(-5)}=2^{-30} \quad\text{\bf{exponents multiplied}}[/tex]
