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