Final answer:
The sum of the first four terms of the arithmetic sequence an = 3n + 7 is 58. This is found by calculating each of the first four terms using the given formula and then summing them.
Step-by-step explanation:
The student is asking to calculate the sum of the first four terms (s4) of the arithmetic sequence defined by the formula an = 3n + 7, where the first term a1 is given as 10.
To find the sum of the first four terms, we will use the given formula to find each term individually and then add them together.
- First term, a1 = 3(1) + 7 = 10
- Second term, a2 = 3(2) + 7 = 13
- Third term, a3 = 3(3) + 7 = 16
- Fourth term, a4 = 3(4) + 7 = 19
To find the sum of these terms, simply add them up:
s4 = a1 + a2 + a3 + a4 = 10 + 13 + 16 + 19 = 58
Therefore, the sum of the first four terms of the sequence is 58.