Fill in the missing term in the geometric sequence. -1, 4, -16, -256

(7, 1)

Explanation:
Test all the ordered pairs in the equations. The one that fits in both is the answer.

(9, 3)
9 + 3 = 8    12 ≠ 8 no
9 - 3 = 6     6 = 6 yes

(6, 0)
6 + 0 = 8    6 ≠ 8 no
6 - 0 = 6     6 = 6 yes

(8, 2)
8 + 2 = 8    10 ≠ 8 no
8 - 2 = 6      6 = 6  yes

(7, 1)
7 + 1 = 8    8 = 8 yes
7 - 1 = 6     6 = 6 yes