在解有关数列问题时,一定要吃透等差数列、等比数列的概念,理解其性质,弄懂题的要领和公式,避免因理解错误而导致失分.一、概念理解错误例1设数列{a_n}中,S_1=1,S_2=2,S_(n+1)-3S_(n+2)S_(n-1)=0(n≥2),判断{a_n}是不是等比数列.思维误区∵S_(n+1)-3S_n+2S_(n-1)=0(n≥2),∴S_(n+1)-S_n=2(S_n-S_(n-1))(n≥2), When solving problems concerning the sequence of numbers, we must thoroughly understand the concept of arithmetic progressions and geometric progressions, understand their nature, understand the essentials and formulae of the problems, and avoid misunderstandings that result in loss of points. In {a_n}, S_1=1, S_2=2, S_(n+1)-3S_(n+2)S_(n-1)=0(n≥2), and it is judged whether {a_n} is a geometric sequence or not. Thinking error ∵S_(n+1)-3S_n+2S_(n-1)=0(n≥2), ∴S_(n+1)-S_n=2(S_n-S_(n-1))(n≥ 2),