Yefim S. answered • 27d

Math Tutor with Experience

By congugate zeros theorem 1 - 2i is also zero.

Then P(x) = (x - 2)(x + 1)(x - 1 - 2i)(x - 1 + 2i) = (x^{2} - x - 2)(x^{2} - 2x + 1 + 4) = (x^{2} - x - 2)(x^{2} - 2x + 5) =

x^{4} - 2x^{3} + 5x^{2} - x^{3} + 2x^{2} + 5x - 2x^{2} + 4x - 10 = x^{4} - 3x^{3} + 5x^{2} + 9x - 10