x_1, x_2, x_3, x_4, x_5, x_6, x_7, x_8, x_9, 
-x_3^2
-x_7^2
-x_9^2
-2*x_1*x_4
-x_1*(1+x_1)
-2*x_2*x_3
-x_2*(1+2*x_1)
-2*x_3*x_6
-2*x_4*x_7
-2*x_6*x_9
-2*x_7*x_8
-2*x_8*x_9
-2*x_3*x_9-x_6^2
-2*x_1*x_5-2*x_2*x_4
-2*x_2*x_6-2*x_3*x_5
-2*x_4*x_8-2*x_5*x_7
-2*x_7*x_9-x_8^2
-2*x_5*x_9-2*x_6*x_8
-2*x_1*x_3-x_2^2-x_3
-2*x_1*x_7-x_4^2+x_7
-2*x_1*x_6-2*x_2*x_5-2*x_3*x_4
-2*x_4*x_9-2*x_5*x_8-2*x_6*x_7
-2*x_2*x_9-2*x_3*x_8-2*x_5*x_6
-2*x_1*x_8-2*x_2*x_7-2*x_4*x_5+x_8
-2*x_1*x_9-2*x_2*x_8-2*x_3*x_7-2*x_4*x_6-x_5^2+x_9
