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Maths questions (Geometric&Arithmetic sequences and series)

How is the geometric sequence formula for the the nth term created?
Any suggestions on websites, please?

What does it mean to prove how the arithmetic formula can be used to find the nth term in the below sequence.
3,7,11

What is the best formula to use to work these out, please?

1) 5,20,40
2) 8,16,24

Please provide workings out so I learn (if that is possible)

Many thanks
(edited 4 years ago)
Reply 1
Avatar for swinroy
swinroy
12
Original post by Teacup:)
How is the geometric sequence formula for the the nth term created?
Any suggestions on websites, please?

What does it mean to prove how the arithmetic formula can be used to find the nth term in the below sequence.
3,7,11

What is the best formula to use to work these out, please?

1) 5,20,40
2) 8,16,24

Please provide workings out so I learn (if that is possible)

Many thanks

the sequence 3,7,11 is an arithmetic sequence with first term ,a = 3 and common difference = 4

so using the formula for the nth term = a + (n-1)d becomes 3 +(n-1)4 = 4n-1
Reply 2
Avatar for erice_2
erice_2
3
Basically a geometric series is a series in which each term is obtained by multiplying the previous term by a constant called the common ration,r.
Nth term= ar^(n-1)
A= first term in the series, r= common ratio which is the factor the series is going up by, n= term your trying to find.

An arithmetic series is one in which the difference between any two consecutive terms is constant and someone put the formula above there
Reply 3
Avatar for swinroy
swinroy
12
Original post by Teacup:)
How is the geometric sequence formula for the the nth term created?
Any suggestions on websites, please?

What does it mean to prove how the arithmetic formula can be used to find the nth term in the below sequence.
3,7,11

What is the best formula to use to work these out, please?

1) 5,20,40
2) 8,16,24

Please provide workings out so I learn (if that is possible)

Many thanks

using a polynomial to get nth term .jpg

The method for finding the nth term is shown above

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