Question

Find the 20^th term from the Last term of the AP: 3, 8, 13, …………., 253.

Answer 1

3, 8, 13, ………….., 253 

a = 3. d = 8 – 3 = 5, a_n = 253 

20^th term from the last term of the AP starting from 253 =? 

253, 258, 263, ………… a₂₀ =? 

a = 253, d = 258 – 253 = 5, n = 20 

a_n = a + (n – 1)d 

a₂₀= 253 + (20 – 1) 5 

= 253 + 19 × 5 

= 253 + 95 

∴ a₂₀ = 348 

∴ 20^th term from the last term of the AP is 348.