What is the nth term of the quadratic sequence 7, 14, 23, 34, 47, 62, 79?

are you asking for the 9th term or the 10th term?

First difference in the sequence is:-

7 9 11 13 15 17

second difference = 2 so nth term contains n2

subtracting n^2 from the sequence

7 14 23 34 47

1 4 9 16 25

= 6 10 14 18 22 this is an AP with first term 6 and common diff = 4

so formula is n^2 + (6 + 4 (n - 1)

= n^2 + 4n + 2 answer