Question

In an ap first term is 5 and common difference is 3 and the nth term is 50 find the value of n and the sum of its first n terms

Answer 1

In an ap first term is 5 and common difference is 3 and the nth term is 50 find the value of n and the sum of its first n terms
Answer:-
in:- (image)
n= 16 and (sum of its first n term)= 440

Answer 2

answer : n = 16 and sum of 16 terms = 440

given, first term of an AP , a = 5

common difference, d = 3

nth term ,Tn = a + (n - 1)d

⇒50 = 5 + (n - 1) × 3

⇒45 = 3(n - 1)

⇒15 = n - 1

⇒n = 16

sum of first n terms = n/2 [2a + (n - 1)d]

so, sum of 16 terms = 16/2 [2 × 5 + (16 - 1) × 3]

= 8 × [10 + 45 ]

= 8 × 55

= 440