∵等比数列{an}共有2n+1项，且奇数项之积为100，偶数项之积为120，∴T奇=a1a3⋅⋅⋅a2n+1=100，T偶=a2a4⋅⋅⋅a2n=120，∴T奇T偶＝a1a3⋅⋅⋅a2n+1a2a4⋅⋅⋅a2n＝a1(a3a2)⋅⋅⋅(a2n+1a2n)＝a1qn＝an+1，即an+1=100...