# Arithmetic and Geometric Progressions Equations

I was struggling to remember these equations for arithmetic and geometric progressions, so decided to make a clear and easy-on-the-eye resource to put up in my bedroom as an ongoing passive revision strategy. Here is a copy in case it helps you. **Although bear in mind that these are given in the formula booklet.**

Teacher recommended

- Created by: Jackarias
- Created on: 17-04-10 15:38

First 92 words of the document:

ARITHMETIC PROGRESSIONS EQUATIONS AND EXAMPLE

th / Last term

+ - 1

Total of first terms of series

( + )

= ×

2

...and if last term is unknown

= [ + - ]

Sum of first natural numbers

= ( + 1)

2

:: EXAMPLE USING SIGMA NOTATION ::

20 20 6

(4 - 1) = (4 - 1) - (4 - 1)

=7 =1 =1

20(3 + 79) 6(3 + 23)

= -

2 2

= 820 - 78 =

GEOMETRIC PROGRESSIONS EQUATIONS

Any term in a geometric progression

= -1

Total of first terms of series

(1 - )

=

1 -

Sum to infinity (convergent series)

=

1 -

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