Question

The no. of terms of AP 3, 7, 11, 17.....
Is to be taken so the sum is 406 is

a. 5
b. 10
c. 12
d. 14​

Answer 1

Answer:

Sum = n/2(2a + (n-1)d)

406 = n/2(6+4n - 4)

406 * 2 = n(2+4n)

406 = n + 2n²

n + 2n²-406 = 0

Solve the equation and u will get the answer.