x_1, x_2, 
-x_2*(x_1^5+8*x_1^4+20*x_1^3+17*x_1^2+6*x_1+8)
-x_2*(x_1^8+14*x_1^7+79*x_1^6+231*x_1^5+376*x_1^4+353*x_1^3+230*x_1^2+152*x_1+64)
-2*(x_1^6+13*x_1^5+67*x_1^4+175*x_1^3+244*x_1^2+172*x_1+48)*x_2
