Add. Write your answer in scientific notation. (4.2 × 10⁹) + (8.1 × 10⁹) What is the sum in scientific notation?

To add the numbers in scientific notation, you need to make sure the exponents are the same. Here, both numbers have the same exponent of 10⁹, so you can directly add the coefficients (the numbers in front).

1. Add the coefficients:

(4.2 + 8.1 = 12.3)

2. Combine with the exponent:

So, you have (12.3 × 10⁹).

3. Convert to proper scientific notation:

Since 12.3 is larger than 10, you need to convert it:

(12.3 = 1.23 × 10¹). Therefore, (12.3 × 10⁹ = 1.23 × 10¹ × 10⁹ = 1.23 × 10¹⁰).

So, the answer in scientific notation is 1.23 × 10¹⁰.