Example 2.1.6.

Use \(\sum\) notation to rewrite the sums:

1. \(\displaystyle 1 + 2 + 3 + 4 + \cdots + 100\)

2. \(\displaystyle 1 + 2 + 4 + 8 + \cdots + 2^{50}\)

3. \(6 + 10 + 14 + \cdots + (4n - 2)\text{.}\)