Consider the following sequence. -1,2,10,23, complete the table table below for the sequence.
n | f(x)

|
|
|
|
|

part b: write a recursive formula for this function.

part c: what kind of function does this sequence appear to represent? justify your answer.

Step-by-step explanation:

a) Apparently, you're to put the given values into a table. The first 5 entries of the table below are the given values. The next few are the result of using the recursive formula. (The formula bar shows the formula that is in the selected cell.)

__

b) The first differences of the terms of this sequence are ...

These are not constant, so the sequence is not arithmetic. The ratios of terms are not constant (2/-1 ≠ 10/2), so the sequence is not geometric.

The second differences are ...

These are constant, which tells us the sequence is a polynomial sequence of 2nd degree (since 2nd differences are constant).

In terms of the differences and second differences we can write the expression for the n-th term

  first difference with term before: a[n] -a[n-1]

  first difference between previous two terms: a[n-1] -a[n-2]

The difference between these two differences is 5, so we can write ...

  (a[n] -a[n-1]) -(a[n-1] -a[n-2]) = 5

Solving for a[n], we get ...

  a[n] = 5 + 2·a[n-1] -a[n-2] . . . . . the desired recursive relation

__

c) As indicated in part (b), this sequence is quadratic. As "proof", we offer that the sequence can be described by an explicit quadratic formula that can be derived from the first sequence term (d0) and the first and second differences (d1 and d2):

  f(n) = d0 + (n-1)(d1 +(n-2)/2·d2) = -1 +(n-1)(3 +(n-2)/2·5)

  f(n) = 5/2n² -9/2n +1

4

step-by-step explanation:

r = 78539458390583095803458309458039485093485 or just 3

step-by-step explanation: