c_1, x_1, x_2, x_3, x_5, x_6, x_7, 
x_5
-c_1*(-3*x_1-2*x_2+112*c_1)
168*c_1^2+3*x_1*x_6+2*x_2*x_6
-39*x_1^2-38*x_1*x_2-8*x_2^2+392*x_3
-72*c_1^5*x_1+64*c_1^5*x_2+3*x_1*x_7+2*x_2*x_7
