Find the roots of the polynomial equation.

-x3 + 5x2 - 11x + 55 = 0

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y = -x3 + 5x2 - 11x + 55 ||x = 5 one root -125 + 125 - 55 + 55 = 0
using Synthetic Divsion
5-15-1155
-50-55

-10-110
results in:
-x^2 - 11 = 0
x^2 + 11 = 0
x^2 = -11
x = ± i√11
roots are: i√11,-i√11,5