Q2 of 176 Page 8

Find the 10th term of the A.P. 10, 5, 0, — 5, — 10, ...

Given: 10, 5, 0, –5, –10,…

To find: 10^th term i.e. t₁₀

Here, a = 10

d = a₂ – a₁ = 5 – 10 = –5

and n = 10

We have,

t_n = a + (n – 1)d

t₁₀ = 10 + (10 – 1)(–5)

= 10 + 9 × –5

t₁₀ = 10 – 45

t₁₀ = –35

Therefore, the 10^th term of the given is –35.

Find the indicated terms in each of the following arithmetic progression:

— 3, — 1/2, 2, ... ; t₁₀,

Find the indicated terms in each of the following arithmetic progression:

a = 21, d = — 5; t_n, t₂₅

Find the 10th term of the A.P.

Find the sum of 20th and 25th terms of A.P. 2, 5, 8, 11, ...