Hello!
To find the simplified expression in scientific notation, we need to multiply 2.1 and 3.5 together, and add the powers together as well.
We add the powers together using the product rule. The product rule says that if there are two exponents with the same base, you add their powers together. This rule can be shown with this: [tex]a^{n} * a^{m} = a^{n + m}[/tex].
2.1 × 3.5 = 7.25
10^2 + 10^5 = 10^7
Therefore, the simplified expression written in scientific notation is 7.35 × 10^7, which is choice B.
