二次根式的运算和化简,主要依据二次根式的定义、性质和有关法则.但对于一些特殊形式的二次根式问题,必须打破常规,采用一些技巧,才能解决问题.这里就二次根式问题介绍一些解题技巧.一、因式分解法例1计算:(2+5-7)2-(2-5+7)2.解原式=(2+5-7+2-5+7)(2+5-7-2+5-7)=22·(25-27)=41 The operation and simplification of secondary roots are mainly based on the definition, properties, and related rules of the secondary roots. However, for some special forms of quadratic root problems, we must break the convention and use some techniques to solve the problem. Here is the secondary root model. Problems introduced some problem-solving techniques. First, the factorization method of the calculation of the law: (2+5-7)2-(2-5+7) 2. The solution of the original = (2+5-7+2-5+7 )(2+5-7-2+5-7)=22(25-27)=41