The essence of the transformation thought of 1 is to reveal the connection and realize the transformation. Except for extremely simple mathematical problems, the solution of every mathematical problem is realized by transforming it into a known problem. In this sense, solving mathematical problems is the process of transforming from unknown to known. Transformation is the basic idea of solving mathematical problems, and the process of solving problems is actually a process of gradual transformation. Transformations in mathematics can be seen everywhere. Such as the transformation from unknown to known, from complex problem to simple problem, from new knowledge to old knowledge, from proposition to proposition, from number to form, from space to plane, from high dimension to low dimension, from multivariate to unitary, from high order to low order, from transcendence to algebra, from function to equation, etc.

There are equivalent transformations and non-equivalent transformations. Before and after the equivalent transformation is a necessary and sufficient condition, so make the transformation as equivalent as possible; If necessary, unequal transformation should be carried out, and restrictions should be attached to maintain equivalence, or the conclusions drawn should be verified.