Question 635489
  <pre><font face = "Tohoma" size = 3 color = "indigo"><b> 
Hi,
g(x)=2x^4-5x^3+9x^2-20x+4 
 2i is a zero, therefore so is -2i and  (x-2i)(x+2i) = x^2 + 4

x^2 + 4 |<span style="text-decoration: overline">2x^4-5x^3+9x^2-20x+4 </span>  

gives: 2x^2  -5x + 1
{{{x = (5 +- sqrt( 17))/(4) }}} the other two roots