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What is the nth term rule of the quadratic sequence below?

6,12,20,30,42,56,72

What is the nth term rule of the quadratic sequence below? 6,12,20,30,42,56,72-example-1

1 Answer

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Answer:

Explanation:

The first term is 6. The difference between the first two terms is 6. The first differences are 6,8,10,12,etc. so the second differences are 2’s.

quadratic formula: an^2+bn+c

2a=second difference=2

3a+b=first differece =6

a+b+c=first term=6

substitute: a=2/2=1, 3(1)+b=6 so b=3, 1+3+c=6 so c=2

nth term= n^2+3n +2

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