Question

3. In an AP:
(1) given a = 5, d= 3, a = 50, find n and S.​

Answer 1

Answer:

n = 16

S = 440

Step-by-step explanation:

a = 5

d = 3

aₙ = a + (n-1)d = 50

ie, 5 + (n-1)*3 = 50

(n-1)*3 = 50 - 5 = 45

n-1 = 45/3 = 15

n = 15 + 1 = 16

So S = n/2(a + aₙ) = 16/2*(5+50) = 8*55 = 440