Stellar Numbers math portfolio

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Title Page, Page Numbers on bottom. This task concerns geometric shapes which lead to stellar, and other special numbers. The special numbers are the total number of dots in a diagram. For example, in a sequence: square numbers with tn values of 1, 4, 9, and 16 correspond to the term numbers 1, 2, 3 and 4, where n is an element of all positive integers. Such is the case with other special numbers, which may produce triangles, or other two dimensional shapes. The main types of special numbers considered in this task are stellar ones. Necessary? > I bet IB doesn’t care. All stars in this portfolio were created with a program titled Stellar-jar. u can talk about all the steps that are part of this portfolio  kinda like here’s what im going to do then do it and for the conclusion tell them what you did. Hence the last step to explain how you arrived at the general statement

 As an example, here are the first four terms of the square number sequence:

          t1                t2                           t3                                       t4

Triangular numbers are the first type of special numbers considered in this task. The term numbers 1, 2, 3, 4, 5 all correspond to the triangular numbers 1, 3, 6, 10 and 15. Here is the visual representation of this.

After the first 5 terms given by the task, by counting the number of dots in terms 6, 7, and 8, the values are 21, 28, and 36 respectively.

The general term could be found in two ways. The first is algebraically. Consider this sequence a relation where the independent variable is term number and the dependent is the number of dots. By calculating the second differences for this set of data (independent as term numbers n and dependent as number of dots, tn), it is clear that a quadratic equation is formed by this relation, because the second differences are constant and not zero.

Let f equal the value of tn . Consider any quadratic equation which can be represented as. The value of a can be found by isolating for a in the equation, where s is the value of the constant differences, and g is the degree of the function. In this case, s=1, and g=2.  

Since a= , by substituting this value into the general equation of a quadratic equation, the only values that now need to be solved for are the b-values and c-values. Therefore the equation as it stands is

f= 0.5n2+bn+c. Now, by substituting in 2 ordered pairs in the equation, two equations are created with only b and c as the unsolved variable in each. From here there is a system of equations that must be solved, and then the values of b and c are found.

  Brackets are fugly, there are symbols, which is what I think you’re looking for .         

Substitute equation [1] into equation [2]:

Substitute c=0 in equation [1]

Therefore the general statement that represents the nth triangular number in terms of n is:

 or  in factored from. Restrictions please.

The second way that this general statement could be derived is with technology. It has already been established that because the second differences are constant and not zero this, the general statement is to the second degree. By entering the n values as the independent variable and the tn values as the dependent variable into a graphing display calculator, and then using the quadratic regression function of the calculator, the calculator creates the same equation as above.

Next the task considers stellar (star) shapes with p vertices, leading to p-stellar numbers. In this case, p, or the number of vertices has a value of 6. Images of the first six stages are shown below.

                          S5                                                                       S6

Now here is a chart showing the number of dots (the stellar number) in these stages. Because these stellar numbers can be considered a sequence (where n is the term number, or the stage and Sn  the number of dots or the stellar number, and n is an element of whole numbers) or a relation,  it also shows up to the third differences.  

When the number of dots were counted, it was noticed that for each added layer there were twelve more dots in that layer. Then after organizing the data into the above table, the value of the second differences (the degree of the relation created by these stellar numbers) was also twelve. Twelve is two times the number of vertices in this case.  Also it is noticed that once the second differences do exist (starting from when n= 3), at that n value, adding the Sn   value at that value of n, the 1st differences at that value, and the 2nd differences at that value, the sum is equivalent to the value of Sn in the next stage.

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An expression for the stellar number at S7 , the 7th term is S7= S6+ (S6-S5) + 12 (where 12 is the value of the second differences).  This was derived through the pattern noticed above where essentially the sum of each row is equivalent to the next Sn value, or at any value of n, where the second differences exist (), adding the Sn   value at that value of n, the 1st differences at that value, and the 2nd differences at that value, the sum is equivalent to the value of Sn in the next stage.

The general statement for the 6-stellar number ...

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