For example, in a constant sequence, each term can be the same constant value, such as {-4, -4, -4 ...}, or there may be negative numbers in arithmetic progression, such as {3,2, 1, 0,-1, -2, -3. ...
Every item in the sequence can be negative, but the number of items in the sequence must be a non-negative positive integer. Just pay attention to the difference between the two.
The number in the series can be negative, and the subscript of the series can only be positive integer. Because the subscript is the number of items, the value of the series changes with the change of the number of items, so the series is a function of the number of items, also called integer function.
An ordered sequence can be two negative numbers. Ordered sequence is a sequence with certain rules, both positive and negative numbers, as long as the sequence is orderly.
Importance of sequence
The investigation of sequence can run through many knowledge points, such as the point sequence problem of analytic geometry and the proof of inequality of derivative sequence. If we can deal with it with the help of scaling skills in turn, we will achieve the effect of "skillfully solving" the problem.
In addition to the college entrance examination, the number sequence is also one of the focuses of the provincial mathematics competition and the national high school mathematics league, and its position is comparable to analytic geometry. It would be a pity to despise the series because the college entrance examination is not difficult and lead to the defeat of the league.
Sequence is a kind of knowledge that is often tested in college entrance examination. There are two types of questions: fill-in-the-blank questions and problem-solving questions, and they often appear in the form of problem-solving questions (even the finale questions), so the importance is self-evident.