Answer:
26^9 = 5,429,503,678,976
Step-by-step explanation:
The applicable rule of exponents is ...
(a^b)(a^c) = a^(b+c)
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[tex]26\cdot26^8=(26^1)(26^8)=26^{1+8}=\boxed{26^9=5\,429\,503\,678\,976}[/tex]
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"Simplest form" often means that all multiplications and divisions are to be carried out.