Question

find the sum to n terms of the gp 1,-1,1,-1,...

Answer 1

Answer:

s=1-(-1)^n/2

Step-by-step explanation:

a=1

r=-1

s=a(1-r^n)/1-r

=1(1-(-1)^n)/1-(-1)

s=1-(-1)^n/2

if n is positive s=0

if n is negative s=1