Monday, 14 March 2016

linear algebra - Complex roots of a 4th degree polynomial



I am trying to find the roots of w(x)=x4+x2+169. I am able to simplify this to (x2+512i)(x2+5+12i). I also know how to solve both expressions using a formula for the square root of a complex number. This seems very tedious. Is there a quicker way? Also, is there a quick way to write down the original polynomial as a product of polynomials with deg2?


Answer



x4+x2+169=(x2+13)225x2=0


hence
(x2+135x)(x2+13+5x)=0


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