Interesting arithmetic sequence

In summary, an arithmetic sequence is a sequence of numbers with a constant difference between consecutive terms. The common difference can be found by subtracting any term from the term before it. Negative terms are also allowed in an arithmetic sequence. The formula for finding the nth term is a<sub>n</sub> = a<sub>1</sub> + (n-1)d, where a<sub>n</sub> represents the nth term, a<sub>1</sub> is the first term, and d is the common difference. Arithmetic sequences can be applied in various real-life situations, such as calculating interest, tracking population growth, and making predictions in mathematical modeling.
  • #1
xholicwriter
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Given N= 1.2.3 + 2.3.4 + ... + n(n+1)(n+2), prove that 4N + 1 is a square (n is a positive integer)
 
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  • #2
It's easy to see that (see www.math.uic.edu/~kauffman/DCalc.pdf on how to find such things)

[tex]1.2.3+...+n(n-1)(n-2)=\frac{(n+1)n(n-1)(n-2)}{4}[/tex]

Thus it suffices to show that

[tex](n+1)n(n-1)(n-2)+1[/tex]

is a square. Which is a much simpler problem.
 
  • #3
Great!
 

Related to Interesting arithmetic sequence

1. What is an arithmetic sequence?

An arithmetic sequence is a sequence of numbers where the difference between consecutive terms is constant. For example, in the sequence 3, 6, 9, 12, the difference between each term is 3.

2. How do you find the common difference in an arithmetic sequence?

The common difference in an arithmetic sequence can be found by subtracting any term from the term before it. This will give you the difference between consecutive terms, which is the same for the entire sequence.

3. Can an arithmetic sequence have negative terms?

Yes, an arithmetic sequence can have negative terms. As long as the difference between consecutive terms remains constant, the sequence is still considered arithmetic.

4. What is the formula for finding the nth term in an arithmetic sequence?

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

5. How can arithmetic sequences be applied in real life?

Arithmetic sequences can be used in many real-life situations, such as calculating interest on a loan, tracking population growth, or predicting future values in financial investments. They can also be used in mathematical modeling to study patterns and make predictions in various fields, such as physics, economics, and biology.

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