Answer:
Explanation:
hello :
the sequence is geometric because : (1/4)/(-1/8) = (-1/8)/(1/16)=-2 = r
the nth term is : An =A1 × r^(n-1)
a common ratio is : r and A1 the first term
in this exercice : r =2 A1 = 1/16
when : n =12 you have the 12rd term A12
A12 = 1/16 × 2^(12-1) = 1/16 × 2^(11)