To find the combined water capacity of the two towers, we need to add the capacities together. The capacities are given as:
- Tower 1: \( 7.35 \times 10^5 \) gallons
- Tower 2: \( 9.78 \times 10^5 \) gallons
First, we can add the numbers in front of the powers of ten:
\[ 7.35 + 9.78 = 17.13 \]
Since both terms have the same power of ten (\(10^5\)), we can combine them:
\[ 17.13 \times 10^5 \]
Now, we need to express \(17.13\) in scientific notation. This can be done by rewriting \(17.13\) as \(1.713 \times 10^1\):
\[ 17.13 \times 10^5 = 1.713 \times 10^1 \times 10^5 \]
Using the rules of exponents, we can combine the powers of 10:
\[ 1.713 \times 10^{1 + 5} = 1.713 \times 10^6 \]
The combined water capacity of the two water towers in scientific notation is:
\[ 1.713 \times 10^6 \]
So, the correct answer is:
1.713×10^6