Arithmetic
Arithmetic
Example 2
Find S7 for the arithmetic sequence 1, 4, 7, 10, 13 …Step 1. Determine the number of terms to add.
S7 = a1 + a2 + a3 + a4 + a5 + a6 +a7
Step 2. Continue the pattern to find the needed terms.
a 6 = 16 and a7 = 19
Step 3. Add the terms.
S7 = 1 + 4 + 7 + 10 + 13 + 16 + 19
S7 = 70