x_1, x_2, x_3, x_4, x_5, 
x_1^2+1
x_1+x_4
2*x_1*x_5^2+x_5^3-2*x_1+x_2
-2*x_1*x_5^2-x_5^3+2*x_1+x_3
2*x_1*x_5^3+x_5^4-2*x_1*x_5+1
