已知数列an中,a1=1,a2=0,对任意正整数n,m(n>m)满足(an)²-(am)²=(an-m)(an+m),则,a199=?打错了。是问a119!

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已知数列an中,a1=1,a2=0,对任意正整数n,m(n>m)满足(an)²-(am)²=(an-m)(an+m),则,a199=?打错了。是问a119!已知数列an中,a1=1

已知数列an中,a1=1,a2=0,对任意正整数n,m(n>m)满足(an)²-(am)²=(an-m)(an+m),则,a199=?打错了。是问a119!
已知数列an中,a1=1,a2=0,对任意正整数n,m(n>m)满足(an)²-(am)²=(an-m)(an+m),则,a199=?
打错了。是问a119!

已知数列an中,a1=1,a2=0,对任意正整数n,m(n>m)满足(an)²-(am)²=(an-m)(an+m),则,a199=?打错了。是问a119!
令n=2,m=1:(a2)²-(a1)²=a1a3;
所以a3=-1;
令n=n>2,m=2:(an)²-(a2)²=(an-2)(an+2),
(an)²=(an-2)(an+2),
所以an/(an+2)=(an-2)/an;
所以a119/a117=a117/a115=…=a3/a1=-1
所以a119/a1=(a3/a1)^((117+1)/2)=(-1)^59=-1;
所以a119=-a1=-1