Question

Find the eighteenth term of the A.P.7.13,19,25,....

Answer 1

A.P. ∴ 7,13,19,25.

Here , a  = 7 , d = t₂ - t₁,   

∴ d  = 13 - 7= 6 

∴ d =  6

∴ t_n = a + (n - 1 ) d

∴t₁₈ = 7 + (18 - 1)(6) 

        = 7 + 17(6)

         = 7 + 102 

    t₁₈ = 109