Question

3. In the A.P: 7.14.21. .... how many terms are to be considered for getting sum
57402​

Answer 1

Answer:

n=127th term

Step-by-step explanation:

the common difference is 7 as 14-7=7

a=7

given the sum is 57402 so we use the formula

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

57402=n/2 (14+7n-7)

57402=n/2 (7+7n)

114804= 7n+7n^2

7n^2+7n-114804=0

n=127th term