$\sum_{i=1}^{x} x + \sum_{i=1}^{x} 2 = 8$
Trying to discover $x$ here, so I made: $x(x-1) + 2(x-1) = 8$
Which should give me the $x$, but instead of an integer I get: $x = \frac{-1\pm\sqrt{41}}{2}$
When the answer should be $x=2$, according to the solution.
What am I doing wrong?