What is the 15th term of the sequence-3,2,7,...?

Answer 1

You have to give more information.
It is not arithmetic , nor is it geometric

I can make it a quadratic ....
term(n) = 3n^2 - 10n + 10
and the three terms you gave me will match.
so
term(15) = 3(225) - 10(15) + 10 = 535

or a cubic
or ....