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 only 1 interaction.
If there are 3 children, there can be 4 interactions.
If there are 4 children, there can be 9 interactions.

Which recursive equation represents the pattern?

Please help, I don't understand!!!

Answer 1

a4 =a3+5=(4+5)=9

the answer is d.

Answer 2

an = an – 1 + 3n – 2

an = an – 1 + 2n – 3

an = an – 1 + (3n – 2)

an = an – 1 + (2n – 3)

These are the answer choices

Answer 3

Yes, i know.

Look at what i plugged in.

Answer 4

Thank you!!!