Question

short answer type question

Answer 1

Hello!

$\textbf{A.P. = 21,\:16,\:11,\:,6,\:1,\:-4\: ...}$

Here,

• First term, a = $\textbf{21}$
• Common difference, d = $\textbf{- 5}$

Then,

♦ $\underline{\sf nth\: term}$ :-

$\boxed{\sf a_{n} = \sf a + ( n - 1 )\: d}$

♦ $\underline{\sf 20th \:term}$ :-

aₙ = a + ( n - 1 ) d

a₂₀ = 21 + ( 20 - 1 ) ( - 5 )

a₂₀ = 21 + ( 19 ) ( - 5 )

$\boxed{\sf a_{20} = \sf - 74}$

♦ $\underline{\sf 25th \:term}$ :-

a₂₅ = 21 + ( 25 - 1 ) ( - 5 )

a₂₅ = 21 + ( 25 - 1 ) ( - 5 )

a₂₅ = 21 + ( 24 ) ( - 5 )

$\boxed{\sf a_{25} = \sf - 99}$

Cheers!

Answer 2

Answer:

WHAT YOU MEAN