The recursive formula for given sequence is: 
And the terms will be expressed as:

Step-by-step explanation:
First of all, we have to determine if the given sequence is arithmetic sequence or geometric. For that purpose, we calculate the common difference and common ratio
Given sequence is:
11,4,-3,-10,-17...
Here

As the common difference is same, given sequence is an arithmetic sequence.
A recursive formula is a formula that is used to generate the next term of the sequence using the previous term and common difference
So, the recursive formula for an arithmetic sequence is given by:

Hence,
The recursive formula for given sequence is: 
And the terms will be expressed as:

Keywords: arithmetic sequence, common difference
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-26 because negative subtract
Answer:
7.5 is the perimeter
Step-by-step explanation:
perimeter is sum of all sides
Х - 15 = 32
х = 32 + 15
x = 47 (answer)
-----------------------
47 - 15 = 32
32 = 32
х - 7.2 = 23,1
х = 23,1 + 7.2
х = 30,3 (answer)
---------------------------
30,3 - 7,2 = 23,1
23,1 = 23,1