Question

1) Find the 128th term for the sequence 9, 4, -1, -6, 11,...

2) Find the 97th term for the sequence -3, 6, -12,...

Answer 1

To determine an nth term of an arithmetic sequence, we use the expression an = a1 + (n-1)d where a1 is the first term in the sequence, n is the number of the term in the sequence and d is the common difference. For a geometric sequence, it is expressed an = a1r^(n-1). We calculate as follows:

1. a128 = 9 + (128-1)(-5)
a128 = -626

2. a97 = (-3)(-2)^(97-1)
a97 = -2.377x10^29