Answer:
not arithmetic
Step-by-step explanation:
An arithmetic sequence has a common difference d between consecutive terms.
Given
[tex]T_{n}[/tex] = 2n² - 1
Substitute in n = 1, 2, 3, 4 to generate the first 4 terms of the sequence
[tex]T_{1}[/tex] = 2(1)² - 1 = 2 - 1 = 1
[tex]T_{2}[/tex] = 2(2)² - 1 = 8 - 1 = 7
[tex]T_{3}[/tex] = 2(3)² - 1 = 18 - 1 = 17
[tex]T_{4}[/tex] = 2(4)² - 1 = 32 - 1 = 31
check the difference between consecutive terms
7 - 1 = 6
17 - 7 = 10
31 - 17 = 14
The differences are not common hence not an arithmetic sequence
