Final answer:
The expression (5.3 × 10⁴) + (1.3 × 10⁴) simplifies to 6.6 × 10⁴, which is already in correct scientific notation with two significant figures, aligning with the original numbers.
Step-by-step explanation:
To simplify the expression (5.3 × 10⁴) + (1.3 × 10⁴), we can add the numerical coefficients since the powers of 10 are the same. We get:
5.3 + 1.3 = 6.6
So the simplified expression is 6.6 × 10⁴. Looking at the options given, the correct scientific notation respecting the significant figures from the original numbers would be:
Option a) 6.6 × 10⁴
It is important to match the number of significant figures, which in this case both original numbers had two significant figures, hence our final answer has two as well.