Question 1139792
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The roots of the polynomial x4+3x3−8x2+2x+4 are:

x1=−0.5556
x2=−4.73943
x3=1.14752+0.44972∗i
x4=1.14752−0.44972∗i


This polynomial has no rational roots that can be found using Rational Root Test.


Roots were found using quartic formulas.
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It means that your problem (as posted) can not be solved by traditional tools.