Question

2+5+8+11+......an=60100.Then what is the value of n

Answer 1

Answer:

200

Step-by-step explanation:

Given : a = 2 and d = 3 Sum = 60100.

Sn = n/2 {2a + (n - 1)d} = 60100

n/2 {4 + (n - 1)3} = 60100

n/2 {4 + 3n - 3} = 60100

n/2 {3n + n} = 60100

3n² + n = 60100 × 2

3n² + n - 120200 = 0

3n² + 601n - 600n - 120200 = 0

n(3n + 601) - 200 (3n + 601) = 0

(n - 200) (3n + 601) = 0

3n = - 601 or n = - 601/3

Here the value of n cannot be negative,

So, n = 200