等式的证明是初中代数的重要内容,它有利于训练学生分析问题、解决问题的能力.因此,等式的证明题在各类初中数学竞赛中频频出现.把一个代数式变换成另一个与它恒等的代数式称为代数式的恒等变形.恒等式的证明,就是通过恒等变形,证明等号两边的代数式相等.其关键是要善于寻找等式两边的差异,并迅速作出消除差异的变形. The proof of equality is an important content of junior high school algebra, it is conducive to train students in the ability to analyze problems and solve problems. Therefore, the proof of equations appear frequently in various types of junior mathematics competitions. Transform one algebraic expression into another with it. The algebraic equation of identity is called the algebraic type of constant deformation. The proof of identity is to prove that the algebraic equations on both sides of the equal sign are equal through the isomorphism. The key is to be good at finding the difference between the two sides of the equation, and quickly make the deformation to eliminate the difference.