1. what is the forty-first term of the 17,9,1?2. what is the sum of the first fourteen term of the sequence 17,9,1?
Answer (1)
Answer:1. the sum of the first 40 terms of the arithmetic sequence -1, -9, -17 is -6280.2.Sequence is 4 + 5, 4 + 5 + 5, 4 + 5 + 5 + 5 so term n = 4 + (5n).15th term is 4 + (5 x 15) = 4 + 75 = 79.Sum of first term plus 15th term = 9 + 79 = 88Sum of second term plus 14th term is 14 + 74 = 88There are 7 pairs (1 15, 2 14, 3 13, 4 12, 5 11, 6 10, 7 9) adding up to 7 x 88 = 616The 8th term is 4 + (5 x 8) = 4+ 40 = 44So the sum is 616 + 44 = 660.
