Question

Find : 

10^th term of the A.P. 1, 4, 7,10,.....

Answer 1

A.P is known for Arithmetic Progression whose common difference = a_n – a_n-1 where n > 0 

a = a₁ = 1, a₂ = 4 

Common difference, 

d = a₂ – a₁ 

= 4 – 1 

= 3 

To find the tenth term of A.P, firstly find a_n 

We know, 

a_n = a + (n-1) d 

Where a is first term or a₁ and d is common difference 

∴ a_n = 1 + (n-1) 3 

⇒ a_n = 1 + 3n – 3 

⇒ a_n = 3n – 2 

When n = 10 : 

a₁₀ = 3(10) – 2 

⇒ a₁₀ = 30 – 2 

⇒ a₁₀ = 28 

Hence,

10^th term of A.P. is 28