Arithmetic Progression Sum Formula

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Arithmetic Progression Sum Formula

\[S_n = (n/2)*(2a_1 + (n-1)d)\]

Variables

Sn = sum of first n terms
n = number of terms
a1 = first term
d = common difference

Description

What is this formula?

This formula calculates the sum of the first n terms of an arithmetic progression.


When to use it

Use it when you need to compute cumulative totals of linearly increasing or decreasing sequences.


Example

Data:

a1 = 2, d = 3, n = 4


Formula:

Sn = (n/2)*(2a1 + (n-1)d)


Substitution:

S4 = (4/2)*(2*2 + (4-1)*3)


Result:

S4 = 26


Applications

Used in finance, physics, and discrete mathematics.


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