Question

Please help! stuck on this last question!
A playground is being designed where children can interact with their friends in certain combinations.
If there is 1 child, there can be 0 interactions.
If there are 2 children, there can be 3 interactions.
If there are 3 children, there can be 12 interactions.
If there are 4 children, there can be 39 interactions.

Which recursive equation represents the pattern?

a. an = an - 1 + 3(n - 1)
b. an = an - 1 + 3(n - 1)
c. an = an - 1 + (3n - 1)
d. an = an - 1 + (n - 1)3

Answer 1

@phi can you pretty please help with this one too?

Answer 2

@thomaster @beccaboo333 @dan815 any body please.. theres a time limit on my test!