Which term of the sequence 1 , -1,1 ,

As per the given question ,

The sequence is :	1	, -	1	,	1	, -	1	,.........-	1
	2		2²		2²		2⁴		2⁸

It is a G.P. with common ratio = – 1 / 2
∴ n^th term = a_n = ar^{n – 1}

⇒	1	=	1	.	1
	- 256		2		( -2)^{n - 1}

⇒	1	=	1
	-2⁷		( -2)^{n - 1}

Equating on both sides , we get
⇒ n – 1 = 7 ⇒ n = 8

Which term of the sequence	1	, -	1	,	1	, -	1	..........is -	1	?
	2		4		8		16		256