Example 4
daniel's cell phone company offers a flat-rate unlimited texting plan for $25 per month. daniel's cost
per text in a given month depends on the number of texts he sent and received that month, according
to the function f(x) shown in the table. use the table to find and interpret the value of f-'(0.05).
25
50
100
150
200
300
400
500
750
1,000
1.00
0.50
0.25
0.17
0.13
0.08
0.06
0.05
0.03
0.03

step-by-step explanation:

cats

, 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

you could deduce the conclusion directly using the facts pertaining to the specific situation.

hope this .