Determine the first 3 elements of the sequence an = -1 + 2n

Solution:
1. Given the formula for the sequence: a_n = -1 + 2n

2. To find the first three terms, substitute n = 1, n = 2, and n = 3 into the sequence formula:

3. For n = 1:
- a_1 = -1 + 2(1)
- a_1 = -1 + 2
- a_1 = 1

4. For n = 2:
- a_2 = -1 + 2(2)
- a_2 = -1 + 4
- a_2 = 3

5. For n = 3:
- a_3 = -1 + 2(3)
- a_3 = -1 + 6
- a_3 = 5

6. The first three elements of the sequence are 1, 3, and 5.