Conversion is one of the most basic mathematical ideas in city middle school mathematics. The combination of numbers and shapes embodies the transformation of numbers and shapes. The idea of function and equation embodies the mutual transformation between function, equation and inequality; The idea of classified discussion embodies the mutual transformation between the part and the whole, so the above three ideas are also the concrete manifestations of transformation and transformation.

However, transformation includes equivalent transformation and non-equivalent transformation, and equivalent transformation requires that the cause and effect in the transformation process are sufficient and necessary; There is only one case of unequal conversion, so the conclusion should be tested, adjusted and supplemented. The principle of transformation is to turn unfamiliar and difficult problems into familiar, easily solved and solved problems, and to turn abstract problems into concrete and intuitive problems; Turn complex problems into simple ones; Turn the general into a special problem; Turn practical problems into mathematical problems and so on, so that problems can be easily solved.

However, transformation includes equivalent transformation and non-equivalent transformation, and equivalent transformation requires that the cause and effect in the transformation process are sufficient and necessary; There is only one case of unequal conversion, so the conclusion should be tested, adjusted and supplemented. The principle of transformation is to turn unfamiliar and difficult problems into familiar, easily solved and solved problems, and to turn abstract problems into concrete and intuitive problems; Turn complex problems into simple ones; Turn the general into a special problem; Turn practical problems into mathematical problems and so on, so that problems can be easily solved.