Question

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

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

can you put the explanation too please (not needed but would be appreciated) :))

Answer 1

90

Let me know if this helps!

Answer 2

It goes +6 +8 +10 so the second differance is 2 you half the second difference to get n^2
You write out the values for n^2
1 4 9 16
Compare with first sequence
6 12 20 30
The difference between these two is +5 +8 +11 and you see this is linear now you solve this to get 3n+2
You add the n^2 to get n^2+3n+2