Sasha noticed that the graph of the sales of yearbooks represented a proportional relationship. how could she have calculated the constant of proportionality by looking at the graph?
she could divide any y-value by its corresponding x-value.
she could divide any x-value by its corresponding y-value.
she could add any y-value to its corresponding x-value.
she could subtract any x-value from its corresponding y-value.

A

Step-by-step explanation:

the answer will be b x² +x-1

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