化归思想是中学数学最基本的思想方法,是解题思想的灵魂,是解题的“心向”.如何恰当地化归,乃是探索解题途径的中心环节.怎样恰当地化归问题呢?下面本文具体举例阐述.1.转换表达,化未知为已知将未知的问题向其等价的表达形式上转化,这是解题的基本方向.例1已知函数f(x)=x+1x+a2,g(x)=x3-a3+2a+1,若存在x1、x2∈[1a,a](a>1)使得|f(x1)-g(x2)|≤ To return to normal thinking is the most basic way of thinking in middle school mathematics, is the soul of problem-solving thinking, is the problem-solving “heart” .How to properly return, but to explore ways to solve the problem of the central link. Here’s a concrete example: 1. Conversion expression, the unknown It is known to transform the unknown problem into its equivalent expression form, which is the basic direction of problem solving.Example 1 It is known that the function f (x = x + 1x + a2, g (x) = x3 - a3 + 2a + 1, if x1, x2∈ [1a, a]