C(m, n)m is at the bottom and n is at the top, which means that N elements are selected from M elements for combination.
Calculation of c:
The number of subscripts is multiplied by the number of themes, and each number must be-1. And then divided by the factorial of the subject.
For example: C5 3 (subscript 5, superscript 3)=(5X4X3)/3X2X 1.
3X2X 1 (i.e. factorial of 3)
Calculation of a:
Just like the first step of C, there is no need to divide the factorial of the above target.
For example A4 2 = 4X3? .
Notes on Mathematics Lecture in Big Class: Interesting Key Card
Activity objectives:
1, learn the addition and subtraction of 8, and you can