an=x^(2n-1)/2^nan+1=x^(2n+1)/2^(n+1)an+1/an=x^2/2讨论如下:(1)x=0 an=0 所以Sn=0(2)x=√2或者x=-√2 an+1/an=x^2/2=1x=√28197 an+1=an=……=a1=√2/2 Sn=na1=√2n/2x=-√2, an+1=an=……=a1...
an=x^(2n-1)/2^nan+1=x^(2n+1)/2^(n+1)an+1/an=x^2/2讨论如下:(1)x=0 an=0 所以Sn=0(2)x=√2或者x=-√2 an+1/an=x^2/2=1x=√28197 an+1=an=……=a1=√2/2 Sn=na1=√2n/2x=-√2, an+1=an=……=a1...