see explanation
step-by-step explanation:
since the sequence is geometric there is a common ratio r between consecutive terms, that is
r = 4 ÷ - 2 = - 2
r = - 8 ÷ 4 = - 2
r = 16 ÷ 8 = - 2
the next term - 13 must be incorrect as it should be - 32 for the sequence to be geometric.
the first 4 terms are therefore geometric with common ratio r = - 2