已知数列{an}满足a1=a,a2=b,a(n+1)=a(n+2)+an,求a2012_数学解答

已知数列{an}满足a1=a,a2=b,a(n+1)=a(n+2)+an,求a2012

人气：471 ℃　时间：2019-11-06 08:50:40

解答

由a(n+1)=a(n+2)+an易知：a1=aa2=b a3=a2-a1=b-aa4=a3-a2=-aa5=a4-a3=-ba6=a5-a4=a-ba7=a6-a5=a.=a1a8=a7-a6=b.=a2a9=a8-a7=b-a.=a3……故an=a,n=6k+1,k∈N+……..b,n=6k+2,k∈N+……..b-a,n=6k+3,k∈N+……..-a,n=6...