Answer:
A. -18·10^6
Step-by-step explanation:
The rules of exponents apply to powers of 10 used in scientific notation. The associative and commutative properties of multiplication also apply.
(a^b)(a^c) = a^(b+c)
The numerical product is ...
[tex](9\cdot10^9)\cdot(-2\cdot10^{-3})=(9)(-2)(10^{9-3})=\boxed{-18\cdot10^6}[/tex]
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Additional comment
Expressed in scientific notation, the result would be ...
[tex]-1.8\cdot10^7[/tex]
Your calculator can perform this multiplication for you.