The sum of the first thirteen terms of the series 3 + 19 + 35 + ... is

This is an arithmetic series where the common difference (d) is 16 (19 - 3 = 16).

The sum (S) of the first n terms of an arithmetic series can be found using the formula:

S = n/2 * (2a + (n - 1)d)

where:

• n is the number of terms (in this case, 13),
• a is the first term (in this case, 3), and
• d is the common difference (in this case, 16).

Substituting these values into the formula gives:

S = 13/2 * (2*3 + (13 - 1)*16) S = 6.5 * (6 + 192) S = 6.5 * 198 S = 1287

So, the sum of the first thirteen terms of the series is 1287.