Question

 Solve for x:
1+2+3+………+x =287

Answer 1

Here, we can see AP forming. As, common difference is same.
i.e. d = 1, a = 1
Sn = 287
n/2[2a + (n - 1)d] = 287
n/2[2(1) + (n - 1)(1)] = 287
n/2[2 + n - 1] = 287
n [2 + n - 1] = 574
2n + n² - n = 574
n² + n - 574 = 0
n = -1/2 + 1/2×√2297 or n = -1/2 -1/2×√2297

I thought it will be a natural number, but surprisingly it's not