**Definition: **an Arithmetic progression is a numerical sequence, each member of which, starting from the second, equal to the previous member, to which **is added** the same number.

**Definition: **the Difference of the arithmetic progression is constant for the sequence number , which is added to each member.

— increasing arithmetic progression

— decreasing arithmetic progression

— **arithmetic progression**

— **the difference of the arithmetic progression**

## Characteristic properties arithmetico progression

**Property:** Any member of an arithmetic progression, starting with the second lorny average arithmetic poperechnogo nastepnego member and Vice versa, if you specified velstelt, then the sequence is an arithmetic progression.

## Formula of nth member of arithmetic progression

## Formula sum of first n members of an arithmetic progression

## Plan the tasks for progression

- Everything that is said in the speech tasks (members progress their amount, etc.) expressed through the first term and the difference of progression.
- Make the equation (or system of equations) according to the problem. In the case when the task of the transition from a geometric progression to an arithmetic progression and Vice versa, to form equations of the normally used characteristic properties of progressions.