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How to distinguish a and c in mathematical permutation and combination?
Students, this question focuses on understanding.

A means arrangement. Arranging is like queuing. Objects are ordered.

C means combination, just like fried rice with eggs and fried rice with eggs. These objects are disordered.

Because of its different meanings, the calculation method is close to:

A(x,y)=y! /(y-x)!

C(x,y)=y! /(y-x)! *x!

Where y> = X.

A deep understanding of concepts is a good way to solve scientific problems logically. What is depth? It depends on your own understanding.