Which of the following are APs?

a, b, c are said to be in AP if the common difference between any two consecutive numbers of the series is the same i.e. b - a = c - b => 2b = a + c
(i) It is not in AP, as the difference between consecutive terms is different
(ii) It is in AP with common difference d = 52 - 2 = 12, a = 2, t5 = 2 + (5 - 1)12
Next three terms are 4, 92, 5
(iii) It is in AP with common difference d = -3.2 + 1.2 = -2, and a = -1.2
Next three terms are a + (5 - 1)d = -9.2, a + (6 - 1)d = -11.2, a + (7 - 1)d = -13.2
(iv) It is in AP with common difference d = -6 + 10 = 4, and a = -10
Next three terms are a + (5 - 1)d = 6, a + (6 - 1)d = 10, a + (7 - 1)d = 14
(v) It is in AP with common difference d = 3 + √2 - 3 = √2, and a = 3
Next three terms are a + (5 - 1)d = 3 + 4√2, a + (6 - 1)d = 3 + 5√2, a + (7 - 1)d = 3 + 6√2
(vi) It is not in AP since 0.22 - 0.2 ≠ 0.222 - 0.22
(vii) It is in AP with common difference d = -4 - 0 = -4 and a = 0,
Next three terms are a + (5 - 1)d = -16, a + (6 - 1)d = -20, a + (7 - 1)d = -24
(viii) It is in AP, with common difference 0, therefore next three terms will also be the same as previous ones, i.e., -12
(ix) It is not in AP since 3 - 1 ≠ 9 - 3
(x) It is in AP with common difference d = 2a - a = a and first term is a,
Next three terms are a + (5 - 1)d = 5a, a + (6 - 1)d = 6a, a + (7 - 1)d = 7a
(xi) It is not in AP, as the difference is not constant
(xii) It is in AP with common difference d = √2 and a = √2,
Next three terms are a + (5 - 1)d = 5√2 = √50, a + (6 - 1)d = √72, a + (7 - 1)d = √98
(xiii) It is not in AP as difference is not constant
(xiv) It is not in AP as difference is not constant
(xv) It is in AP with common difference d = 52 - 1 = 24 and a = 1,
Next three terms are a + (5 - 1)d = 97, a + (6 - 1)d = 121, a + (7 - 1)d = 145