Question

The sum of first n terms of AP 5,9,13..... is 230.
Then find the 'n' by solving suitable quadratic Equation in 'n'.​

Answer 1

Step-by-step explanation:

Sn = 230

From the A.P,

a = 5

d = 9 - 5 = 4

By formula, Sn = n/2 [2a + (n-1)d]

Hence 230 = n/2 [10 + (n-1)4]

From picture, solve n to get two values

One value will be negative, which will be discarded as n cannot be negative.

Hence positive value is your answer

Answer 2

Answer:

n = -16.5 or = 10

Step-by-step explanation:

check the attached file for step by step explanation

thank you