(%i1) load ( odes ) $
(%i2) eq : x ^ 6 + x ^ 5 + 2 · x ^ 4 2 · x ^ 3 + x ^ 2 + 2 · x 1 = 0 ;
x 6 + x 5 + 2 x 4 2 x 3 + x 2 + 2 x 1 = 0
(%i3) P ( x ) : = x ^ 6 + x ^ 5 + 2 · x ^ 4 2 · x ^ 3 + x ^ 2 + 2 · x 1 ;
P ( x ) := x 6 + x 5 + 2 x 4 + ( 2 ) x 3 + x 2 + 2 x 1
(%i4) solvet ( eq , x ) ;
[ x = 1 , x = 3 %i 1 2 , x = 3 %i + 1 2 , x = 2 7 cos ( atan ( 3 3 2 ) 3 π 3 ) + 1 3 , x = 2 7 cos ( atan ( 3 3 2 ) π 3 ) + 1 3 , x = 2 7 cos ( atan ( 3 3 2 ) + π 3 ) + 1 3 ]
(%i5) wxplot2d ( [ P ( x ) ] , [ x , 1 . 5 , 2 ] ) , wxplot_size = [ 640 , 480 ] $
 (Graphics)

Created with wxMaxima.

The source of this Maxima session can be downloaded here.