For each positive integer,the quantity [size=150]S[/size]n i

For each positive integer,the quantity Sn is defined such that Sn+2=(Sn)^2 - S(n+1).in addition ,S2=1.then which of the following must be true.

a) S4 +S3 +1=0
b) (S1)^2 +S4 +2=0
c) if S1=-1 then S4 is also equal to -1.
d) if S4 =-7 then S1=-2.
e) if S1 =-3 then S4= -7