Find sum of all real such that the below equation is true.
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For any x it is true that:
e x = 1 + x + 2 ! x 2 + 3 ! x 3 + 4 ! x 4 + 5 ! x 5 . . .
So for any x = 0 :
e x = 1 + x + 2 ! x 2 + 3 ! x 3 + 4 ! x 4
But for x = 0 all the extra terms become 0 so the equation holds true. Therefore, the sum of the roots is 0.
Note: I feel like i explained it poorly or maybe i've made a mistake. Please provide a better solution.