Matrix d2 using coeff as given in cramer 's rule
let d2 = [ [ coeff [ 0 ] [ 0 ] , coeff [ 0 ] [ 3 ] , coeff [ 0 ] [ 2 ] ] , [ coeff [ 1 ] [ 0 ] , coeff [ 1 ] [ 3 ] , coeff [ 1 ] [ 2 ] ] , [ coeff [ 2 ] [ 0 ] , coeff [ 2 ] [ 3 ] , coeff [ 2 ] [ 2 ] ] ] ;