Question

The nth element of the sequence -1 ,2, -4, 8....is
(a)(-1)^n2^n-1
(b)2^n-1
(c)2^n
(d) none of these
plzz reply with explanation

Answer 1

Answer:- Option a)

Step By Step Explanation:-

After the last step we shall simplify the answer,

$(-1)(-2)^{n-1}\\\;\\=(-1)(-2)^n\times(-2)^{-1}\\\;\\=(-1)(-2)^n\times\frac{1}{-2}\\\;\\=\frac{1}{2}\times(-2)^n\\\;\\=\frac{1}{2}\times(-1)^n\times2^n\\\;\\=(-1)^n\times2^n\times2^{-1}\\\;\\=(-1)^n\;2^{n-1}$

Hence, Option a) is correct.

Answer 2

Answer:

Step-by-step explanation: