Final answer:
The sum 2^5 + 3^5 + 4^5 + ... + 7^5 can be written in summation notation as Σ_{i=2}^{7} i^5, which represents the sum of the fifth powers of the integers from 2 to 7.
Step-by-step explanation:
To express the sum 25 + 35 + 45 + ... + 75 using summation notation, we identify the pattern in the terms of the series. Each term is a successive integer raised to the fifth power. The first term starts with 2 raised to the fifth power and the last term ends with 7 raised to the fifth power.
The sum can be expressed in summation notation as Σi=27 i5, where i is the index of summation that starts at 2 and ends at 7, and i5 is the general term in the series. This compactly represents the sum of the fifth powers of the integers from 2 to 7.