2008年全国卷Ⅰ理科21题是数列、平面向量与圆锥曲线在符号层面上的整合问题,之所以这样说的缘由是因为在剥去覆盖于表层的数列、平面向量的面纱后,深入挖掘此题并寻求题目最后结果用到的主干知识就是双曲线的几何性质.而发现这一点后怎样找到对于此题的解题突破口就是关键了很多考生不是被题目的表面现象所迷惑无从下手 In the National Science Book I, Volume 21 in 2008, the issue of the integration of sequences, plane vectors, and conic curves at the symbol level, the reason for this is because after ripping off the veil covering the surface series and plane vectors The main knowledge used in the topic and seeking the final result of the topic is the geometric nature of the hyperbola. After finding this point, how to find the solution to the problem is the key to the breakthrough. Many candidates are not confused by the surface phenomena of the topic.