已知数列{an}中,a3=2,a7=1,若{1/an+1}为等差数列,则a11等于?

已知数列{an}中,a3=2,a7=1,若{1/an+1}为等差数列,则a11等于?
已知数列{an}中,a3=2,a7=1,若{1/an+1}为等差数列,则a11等于?

已知数列{an}中,a3=2,a7=1,若{1/an+1}为等差数列,则a11等于?
a3=2,a7=1,若{1/(an+1)}为等差数列
公差d=（1/a7+1-1/a3+1)/(7-3)=1/24
1/(a11 +1)=1/3 +1/24 *(11-3) =2/3
a11=1/2