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 help?

Answer 2

I think its B

Answer 3

or A but I'm not pisitive

Answer 4

What's the difference between A and B?

Answer 5

Choices A and B (as written) are the same formula. I assume there is a typo ?

Answer 6

no I copied and pasted it.

Answer 7

shoot I see what i did...
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 8

D. an = an – 1 + (n – 1)^3