Determining if a sequence is arithmetic

In summary, the given sequence is an arithmetic sequence with a common difference of 6. The first 5 terms are 2, 8, 14, 20, and 26.
  • #1
fluffertoes
16
0
Question:

Find the first 5 terms of this series and determine if it is an arithmetic sequence.

An= 2 + 6n

Help please!
 
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  • #2
Re: Sequences and series help ASAP please!

fluffertoes said:
Question:

Find the first 5 terms of this series and determine if it is an arithmetic sequence.

An= 2 + 6n

Help please!

If we have an AP, then we must have:

\(\displaystyle a_{n+1}-a_{n}=C\) where C is some constant...is this what we have?
 
  • #3
Re: Sequences and series help ASAP please!

MarkFL said:
If we have an AP, then we must have:

\(\displaystyle a_{n+1}-a_{n}=C\) where C is some constant...is this what we have?

All the info i was given is what I put in the original question up there, yikes
 
  • #4
Re: Sequences and series help ASAP please!

fluffertoes said:
All the info i was given is what I put in the original question up there, yikes

We are given:

\(\displaystyle a_{n}=2+6n\)

Therefore:

\(\displaystyle a_{n+1}=2+6(n+1)\)

So, what is the difference:

\(\displaystyle a_{n+1}-a_{n}\) ?
 
  • #5
Re: Sequences and series help ASAP please!

MarkFL said:
We are given:

\(\displaystyle a_{n}=2+6n\)

Therefore:

\(\displaystyle a_{n+1}=2+6(n+1)\)

So, what is the difference:

\(\displaystyle a_{n+1}-a_{n}\) ?

1? I'm not sure
 
  • #6
Re: Sequences and series help ASAP please!

fluffertoes said:
1? I'm not sure

Let's work it out...

\(\displaystyle a_{n+1}-a_{n}=\left(2+6(n+1)\right)-\left(2+6n\right)=\left(2+6n+6)\right)-\left(2+6n\right)=(2+6n)+6-(2+6n)=6\)

This tells us that any two successive terms in the given sequence differ by 6, which is a constant, and therefore we do have an arithmetic sequence. :)
 

1. How do you determine if a sequence is arithmetic?

To determine if a sequence is arithmetic, you need to check if there is a constant difference between each consecutive term. If there is a consistent difference, the sequence is arithmetic.

2. What is the formula for an arithmetic sequence?

The formula for an arithmetic sequence is an = a1 + (n-1)d, where an represents the nth term, a1 is the first term, and d is the common difference.

3. Can an arithmetic sequence have a negative common difference?

Yes, an arithmetic sequence can have a negative common difference. This means that the terms in the sequence are decreasing in value.

4. What is the difference between an arithmetic sequence and a geometric sequence?

An arithmetic sequence has a constant difference between each consecutive term, while a geometric sequence has a constant ratio between each consecutive term. In an arithmetic sequence, the difference between terms stays the same, whereas in a geometric sequence, the terms are multiplied by a constant factor.

5. How can you use the arithmetic mean to determine if a sequence is arithmetic?

The arithmetic mean of a sequence is the average of all the terms in the sequence. If the arithmetic mean is equal to the first term in the sequence, then the sequence is arithmetic. If the arithmetic mean is not equal to the first term, then the sequence is not arithmetic.

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