The service elevator in a high-rise building travels between the lowest underground parking level and the seventeenth story of the building. The lowest parking level is 15 meters below street level, and the seventeenth story is 51 meters above street level. If the elevator rises at a rate of 2 meters per second, how long, in seconds, could a person ride the elevator when starting from lowest level? Assume the elevator makes no extra stop.

answer:

c. the third graph

, 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

d. all of the above

step-by-step explanation: