Question

The sum of first 20 and first 50 terms of an ap is 420 and 2550

Answer 1

this is the answer of your question

Answer 2

Answer:

The A.P is: 2, 4, 6, 8,.......  

Step-by-step explanation:

Let the first term = a

and, Common difference = d

For finding the nth term, we use formula

Sₙ = n ÷ 2 [2a + (n - 1) d ]

where, Sₙ = Sum of nth term

a = First term

n = number of term

d = difference

thus, we get equations,

420 = 10 [ 2a + 19d]

and 2550 = 25 [ 2a + 49d]

Solving both equation. We get,

a = 2 and d = 2

Thus, the A.P is: 2, 4, 6, 8,.......