EXPLANATION.
Series : 2, 7, 12, 17, . . . . .
As we know that,
General term of an ap.
⇒ Tₙ = a + (n - 1)d.
Using this formula in this question, we get.
First term = a = 2.
Common difference = d = b - a = 7 - 2 = 5.
Put the values in the expression, we get.
⇒ Tₙ = 2 + (n - 1)(5).
⇒ Tₙ = 2 + 5n - 5.
⇒ Tₙ = 5n - 3.
∴ Recursive formula is : Tₙ = 5n - 3.
MORE INFORMATION.
Supposition of terms in an A.P.
Three terms as : a - d, a, a + d.
Four terms as : a - 3d, a - d, a + d, a + 3d.
Five terms as : a - 2d, a - d, a, a + d, a + 2d.