Yang Hui Triangle has another feature:
(1) From the second line to the fifth line, the number of each line (such as the third line 12 1) is the product of the number of the previous line and 1 1.
(2) It can be written as115 =161051.
So the answer is:1a6+6a5b+15a4b2+20a3+15a2b3+6b4+1b5, 1 1,16/.
The skills of arranging mathematical winter vacation homework are as follows:
1, to remind students to do their homework repeatedly