Answer
a) n=1
$(-r)^{n-1}$
n = 0
$(-r)^{n}$
b) n = 1
$(-1) (-r)^{n}$
n = 0
$(-1) (-r)^{n+1}$
Work Step by Step
a) For n = 1
Formula =$(-r)^{n-1}$
For n = 0
Formula = $(-r)^{n}$
b) For n = 1
Formula = $(-1) (-r)^{n}$
For n = 0
Formula = $(-1) (-r)^{n+1}$
