Saturday, May 3, 2014

Decide whether the sequence can be represented perfectly by a linear or a quadratic model. If so, then find the...

Firstly we need to determine whether the series is linear or quadratic. A linear sequence is a sequence of numbers in which there is a first difference between any consecutive terms is constant. However, a quadratic sequence is a sequence of numbers in which there is a second difference between any consecutive terms is constant. 

Let's determine if the above sequence has a first difference: 





From above we observe there is no first difference, now let's determine the second difference: 




From above we observe that the second difference is constant. Therefore the sequence is perfectly quadratic.


Let's determine the quadratic model using the following formula: 



where: T_n = term value, ,n = term, variables: a,b,c


 = second difference




Let's find variable b: 


  first difference between term 2 and term 1


 (substitute for a and first difference between term 2 and term1)



Lastly we are finding variable c: 


 value of term 1


 (substitute for a, b and value of term 1



Now we have determined the variables, we can develop our model: 



Let's double check our formula using term 4: 



SUMMARY: 


Sequence: Quadratic


Model: 

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