PLEASE HELP!! WILL MARK BRAINLIEST! 4. Find the sum of the first 21 terms in a series where a = 20 and = 99.
6. Find the sum of the first 50 terms in a series where a = 4 and = 196.
7. Find the sum of the first 100 terms in a series where a = 0 and = 99.
8. Find the sum of the first 10 terms in an arithmetic series where = 7 and = 13.
9. Find the sum of the first 10 terms in an arithmetic series where = 15 and = 45.
10. Find the sum of the first 30 positive multiples of 5.
Part B
Directions: Now, find n and Sn for each of the following arithmetic series below.
11. 5 + 11 + 17 + 23 + …+ 101
12. 2 + 4 + 6 + 8+ …+ 60
13. 46 + 43 + 40 + …+ 16