(i) ( a_1 = 2 ), ( d = 13 )

[ \begin{align*} a_1 &= 2 \ a_2 &= 2 + 13 = 15 \ a_3 &= 15 + 13 = 28 \end{align*} ]

Answer: ( 2, 15, 28 )

(ii) ( a_1 = 12 ), ( d = -13 )

[ \begin{align*} a_1 &= 12 \ a_2 &= 12 - 13 = -1 \ a_3 &= -1 - 13 = -14 \end{align*} ]

Answer: ( 12, -1, -14 )