Question

Find the 20th term from the end of the AP 253,248,243,...,3​

Answer 1

Given :–

• a₁ = 253
• a₂ = 248
• a₃ = 243
• l = 3
• n = 20

To Find :–

• 20th term of an A.P. (Arithmetic Progression).

Solution :–

Common Difference (d) = a₂ – a₁ = a₃ – a₂

→ 248 – 253 = 243 – 248

→ –5 = –5

• d = –5

→ $\sf a_{n}$ = a₁ + (n – 1)d

→ $\sf a_{20}$ = 253 + (20 – 1)(–5)

→ $\sf a_{20}$ = 253 + (19)(–5)

→ $\sf a_{20}$ = 253 – 95

→ $\sf a_{20}$ = 158

Hence,

The 20th term of this Arithmetic Progression (A.P.) is 158.

Additional Information :–

What is an Arithmetic Progression (A.P.) ?

⟹ Arithmetic Progression is also known as Arithmetic Sequences.

⟹ It is a sequence of numbers which have same difference between the sequences.

⟹ It is also that decreases and increases in the sequences.

⟹ Example :– 2,4,6,8,10..... it is an A.P. (Arithmetic Progression) because it's common difference or same amount between each numbers is 2.