已知数列(An)中,A1=1/3,AnAn-1=An-1-An(n>=2),数列Bn满足Bn=1/An,求数列Bn的通项公式需要详细的步骤

问题描述:

已知数列(An)中,A1=1/3,AnAn-1=An-1-An(n>=2),数列Bn满足Bn=1/An,求数列Bn的通项公式
需要详细的步骤

AnAn-1=An-1-An
(An-1-An)/AnAn-1=(1/An)-(1/An-1)=1
则Bn为B1=3 d=1 的等差数列
所以Bn=3+(n-1)*1=n+2

AnAn-1=An-1-AnAnAn-1+An=An-1An=An-1/(A(n-1)+1) n>=2 A1=1/3A2=A1/(A1+1) =1/3/(1/3+1)=1/4A3=A2/(A2+1)=A1/(A1+1) / (A1/(A1+1)+1)=A1/(A1+A1+1)=A1/(2A1+1)=1/3/(2/3+1) =1/5A4=A3/(A3+1)=A1/(2A1+1) / ( A1/(2A...