Is it a drag and drop method to use recursive equation in mathematics

Is it a drag and drop method to use recursive equation in mathematics

Gradually reduce the items of the formula until the calculation process of the result is written in the format. It can be "even" or "recursive". Recursive: the formula is written in two empty spaces, and the top space of the equal sign is written and aligned. Gradually reduce the items of the formula until the calculation process of the result is written in the format. The purpose of the two is the same, and the form is required to exist