Question

Find the sum of n first natural numbers is 496 ,find the number of terms

Answer 1

Number of terms = 31.

Explanation:

Sum of n terms of an A S with first term 1 and common difference 1:-

496 = (n/2)(2(1) + 1(n - 1))

496 = (n/2)(n + 1)

n^2/2 + n/2 = 496 Multiply through by 2:-

n^2 + n = 992

n^2 + n - 992 = 0

(n - 31)(n + 32) = 0

n = 31 (we ignore the negative).