x_1, x_2, x_3, x_4, 
-4*x_1*x_3-x_1*x_4+16000*x_1-10000
-x_2*x_3-4*x_2*x_4+16000*x_2-10000
-40*x_1^3-10*x_1*x_2^2+4*x_1*x_3+x_1*x_4+16000*x_1-10000
-10*x_1^2*x_2-40*x_2^3+x_2*x_3+4*x_2*x_4+16000*x_2-10000
