Question

plz solve this question.......​

Answer 1

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

To find n:

865 = (n/2)(2×100 + (n - 1)×(-3))

2×865 = n (200 - 3n + 3)

1730 = 203n - 3n^2

3(n^2) - 203n + 1730 = 0

On solving the quadratic equation, we get the roots 10 or 173/3. Since the number of terms must be an integer, the sum of the first 10 numbers is 865.

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