Respuesta :

Answer:

Ans. -8

Step-by-step explanation:

n = 4 for 4th term

B(4) = 1 (-2)^ 4-1 ( here B is 'a' ie. B4 is same as a4)

= 1 (-2) ^3 (2^3 is 8 , -2^3 is -8 )

= 1 (-8)

= -8

hence -8 is the fourth term in the sequence.