Suppose one person in your team has two x2‑tiles, three x‑tiles, and one unit tile on his desk and another person has one x2‑tile, five x‑tiles, and eight unit tiles on her desk. You decide to put all of the tiles together on one desk. What is the name for this new group of tiles?

d

step-by-step explanation:

, and

for

step-by-step explanation:

we can analyze the pattern at which the terms increase. let us denote , , , so that we can call

note the following:

the pattern: to get the next term value, we just add the next term number (e.g. 1st, 2nd, to the previous term value (term values are the given numbers in the question, 1, 3, 6, 10, 15,

from , to get to , we add

from , to get to , we add

etc.

we need to form a recursive formula, a formula that has the next term as a function of the previous term. so a possible recursive formula can be

, and for