Question 1119500
The general form for the nth term of a geometric sequence is a_n = ar^(n-1)
where a = the 1st term and r is the common ratio

(a) In this case, r =-4/4 = -1, and a = 4
Thus a_n = 4(-1)^(n-1)

(b) In this case, r = 8/16 = 1/2, a = 16
Thus a_n = 16(1/2)^(n-1)