Question

2)数列{ an }中，a1=1，an+1= 2an/an+2求an通项公式。（其中n，n+1为下脚标）

要有步骤的哦

Answer 1

a(n+1)=2an/(an + 2)

1/a(n+1)= (an + 2)/2an = 1/2 + 1/an

1/a(n+1) - 1/an = 1/2 所以1/an 为等差数列，公差是1/2

1/an = 1/1 + 1*(n-1)/2 = (n+1)/2

an = 2/(n+1)