Say I have a system of equations of the following form: a_1 A^2 + b_1 B^2 + c_1 C^2 + d_1 = f_1 a_2 A^2 + b_2 B^2 + c_2 C^2 + d_2 = f_2 a_3 A^2 + b_3 B^2 + c_3 C^2 + d_3 = f_3 Where a,b,c,d,f are coefficients, and A,B and C are unknown variables. 1. Can we write them in terms of two variables only? 2. Can we write them in terms of one variable only?