There are 3 cases when
$x^y= 0$ when y = 0 or x =1 or x = -1 and y even
hence $(n^2-n-1)^{n+2}= 1$
when
1) n+2 = 0 or n = -2
or
2) $n^2 -n -1 = 1$
or $n^2 - n -2 = 0$ or $(n-2)(n+1) = 0$ giving n = 2 or -1
or
3) $n^2 -n -1 = -1 $ and n+2 is even
in this case
$x = -1 =>n^2 -n -1 = -1$ $n^2-n=0$ so n= 0 or n =1. but n+2 need to be even so n= 0
so solution set n= 0 or 2 or -2 or -1
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