General formula
1. 1/n(n+ 1)= 1/n- 1/(n+ 1)
2. 1/(2n- 1)(2n+ 1)= 1/2[ 1/(2n- 1)- 1/(2n+ 1)]
3. 1/n(n+ 1)(n+2)= 1/2[ 1/n(n+ 1)- 1/(n+ 1)(n+2)]
4. 1/(√a+√b)=[ 1/(a-b)](√a-√b)
5.n n！ =(n+ 1)！ -No!
The essence of split term summation split term method is to decompose each term (general term) in the sequence, then recombine and eliminate some terms, and finally achieve the purpose of summation. The relationship between multiples of general term decomposition (split term). This deformation is characterized by the fact that after each item in the original series is split into two items, most of the items in the middle cancel each other out. There are only a few things left. Note: The remaining projects have the following characteristics. 1. The positions before and after the other items are symmetrical. 2. The positivity and negativity of other projects are opposite.
Related examples
The above are the formulas and knowledge points I have compiled, hoping to help everyone.