x_1, x_2, x_3, x_4, 
x_2^2-4*x_2+4
3*x_1^5+26*x_1^3+75*x_1+24*x_3
x_1^6+9*x_1^4+27*x_1^2+27
-x_1^4+4*x_1^2*x_2-14*x_1^2+12*x_2-33
5*x_1^4+54*x_1^2-48*x_2+48*x_4+117
