Sum rule: ∑ j =1+2+3+…+N. Capital σ is used for mathematical sum symbols, such as ∑Pi, where i= 1, 2, 3, ..., t, which is the sum ..+angle of p1+p2+p. ∑ formula calculation: the number indicating the beginning and end. For example, the following n=2, and the number 10 above means from 2 to 10.
As follows:
1. Introduction
∑ is a summation symbol, with English name sigma and Chinese name Sigma. It is the eighteenth letter of the Greek alphabet, also known as finalsigma.
It is widely used in mathematics and physics. In mathematics, we use lowercase letter σ to represent standard deviation, while in physics, we use lowercase letter σ to represent area density or valence bond of * * * *. These symbols have specific meanings and usages in engineering materials and chemistry.
Calculation method of summation formula: The summation formula is S=( 1+n)*n/2, and finding S is essentially a general formula for finding {an}, so we should pay attention to understanding its meaning. Common methods include formula method, dislocation subtraction method, anti-addition method, grouping method, split term method, mathematical induction method, general term reduction method and union term summation method.
2. The method of summation
There are seven methods for the summation formula of series: formula method, column item elimination method, dislocation subtraction method, decomposition method, grouping method, reverse order addition, multiplication and wrong item subtraction method. The details are as follows: Formula method. Formula method is a method to solve a quadratic equation with one variable, and it also refers to the application of a formula to calculate something.
For example, to find the sum of 1 ~ 100, the calculation method is (1+100)/2 *100 = 5050. In the law of continuous addition in mathematics, the law of continuous addition of natural numbers is: (the first term+the last term) x term ÷2. This is based on Gauss theorem. The first term here refers to the addend at the beginning and the last term refers to the addend at the end.
for instance
For example:100 ∑ i =1+2+3+4+5+100i =1. The summation formula is I, and the range of I is determined by two conditions. The initial value of I is I = 1. +x)=8？ +8+9? +9+ 10? + 10+...+98? +98x=8
The formula that needs to be summed is (x? +x), the value range of x is determined by two conditions, the initial value of x is x=8 and the final value is x=98, so the value of x from 8 to 98 is substituted into the formula (x? +x) can be obtained by addition. 8? +8+9? +9+ 10? + 10+...+98? +98。