f := a6*y^2 + a5*y*z + a4*y*w + a3*z^2 + a2*z*w + a1*w^2;

g := b6*y^2 + b5*y*z + b4*y*w + b3*z^2 + b2*z*w + b1*w^2;

h := c6*y^2 + c5*y*z + c4*y*w + c3*z^2 + c2*z*w + c1*w^2;

d1 := [ [  a6, a5, a4, a3, a2, a1, 0,  0,  0,  0,  0,  0,  0,  0,  0],
            [0,  0,  a6, 0,  a5, a4, 0,  a3, a2, a1, 0,  0,  0,  0,  0],
            [0,  a6, 0,  a5, a4, 0,  a3, a2, a1, 0,  0,  0,  0,  0,  0],
            [0,  0,  0,  a6, 0,  0,  a5, a4, 0,  0,  a3, a2, a1, 0,  0],
            [0,  0,  0,  0,  a6, 0,  0,  a5, a4, 0,  0,  a3, a2, a1, 0],
            [0,  0,  0,  0,  0,  a6, 0,  0,  a5, a4, 0,  0,  a3, a2, a1],
            [0,  0,  0,  b6, 0,  0,  b5, b4, 0,  0,  b3, b2, b1, 0,  0],
            [0,  0,  0,  0,  b6, 0,  0,  b5, b4, 0,  0,  b3, b2, b1, 0],
            [0,  b6, 0,  b5, b4, 0,  b3, b2, b1, 0,  0,  0,  0,  0,  0],
            [0,  0,  b6, 0,  b5, b4, 0,  b3, b2, b1, 0,  0,  0,  0,  0],
            [0,  0,  0,  0,  0,  b6, 0,  0,  b5, b4, 0,  0,  b3, b2, b1],
            [0,  0,  0,  0,  0,  c6, 0,  0,  c5, c4, 0,  0,  c3, c2, c1],
            [0,  0,  c6, 0,  c5, c4, 0,  c3, c2, c1, 0,  0,  0,  0,  0],
            [0,  c6, 0,  c5, c4, 0,  c3, c2, c1, 0,  0,  0,  0,  0,  0],
            [0,  0,  0,  0,  c6, 0,  0,  c5, c4, 0,  0,  c3, c2, c1, 0 ] ];

d2 := [[ b6, b5, b4, b3, b2, b1, 0,  0,  0,  0,  0,  0,  0,  0,  0],
            [0,  0,  b6, 0,  b5, b4, 0,  b3, b2, b1, 0,  0,  0,  0,  0],
            [0,  b6, 0,  b5, b4, 0,  b3, b2, b1, 0,  0,  0,  0,  0,  0],
            [0,  0,  0,  b6, 0,  0,  b5, b4, 0,  0,  b3, b2, b1, 0,  0],
            [0,  0,  0,  0,  b6, 0,  0,  b5, b4, 0,  0,  b3, b2, b1, 0],
            [0,  0,  0,  0,  0,  b6, 0,  0,  b5, b4, 0,  0,  b3, b2, b1],
            [0,  0,  0,  c6, 0,  0,  c5, c4, 0,  0,  c3, c2, c1, 0,  0],
            [0,  0,  0,  0,  c6, 0,  0,  c5, c4, 0,  0,  c3, c2, c1, 0],
            [0,  c6, 0,  c5, c4, 0,  c3, c2, c1, 0,  0,  0,  0,  0,  0],
            [0,  0,  c6, 0,  c5, c4, 0,  c3, c2, c1, 0,  0,  0,  0,  0],
            [0,  0,  0,  0,  0,  c6, 0,  0,  c5, c4, 0,  0,  c3, c2, c1],
            [0,  0,  0,  0,  0,  a6, 0,  0,  a5, a4, 0,  0,  a3, a2, a1],
            [0,  0,  a6, 0,  a5, a4, 0,  a3, a2, a1, 0,  0,  0,  0,  0],
            [0,  a6, 0,  a5, a4, 0,  a3, a2, a1, 0,  0,  0,  0,  0,  0],
            [0,  0,  0,  0,  a6, 0,  0,  a5, a4, 0,  0,  a3, a2, a1, 0 ] ];

d3 := [ [ c6, c5, c4, c3, c2, c1, 0,  0,  0,  0,  0,  0,  0,  0,  0],
            [0,  0,  c6, 0,  c5, c4, 0,  c3, c2, c1, 0,  0,  0,  0,  0],
            [0,  c6, 0,  c5, c4, 0,  c3, c2, c1, 0,  0,  0,  0,  0,  0],
            [0,  0,  0,  c6, 0,  0,  c5, c4, 0,  0,  c3, c2, c1, 0,  0],
            [0,  0,  0,  0,  c6, 0,  0,  c5, c4, 0,  0,  c3, c2, c1, 0],
            [0,  0,  0,  0,  0,  c6, 0,  0,  c5, c4, 0,  0,  c3, c2, c1],
            [0,  0,  0,  a6, 0,  0,  a5, a4, 0,  0,  a3, a2, a1, 0,  0],
            [0,  0,  0,  0,  a6, 0,  0,  a5, a4, 0,  0,  a3, a2, a1, 0],
            [0,  a6, 0,  a5, a4, 0,  a3, a2, a1, 0,  0,  0,  0,  0,  0],
            [0,  0,  a6, 0,  a5, a4, 0,  a3, a2, a1, 0,  0,  0,  0,  0],
            [0,  0,  0,  0,  0,  a6, 0,  0,  a5, a4, 0,  0,  a3, a2, a1],
            [0,  0,  0,  0,  0,  b6, 0,  0,  b5, b4, 0,  0,  b3, b2, b1],
            [0,  0,  b6, 0,  b5, b4, 0,  b3, b2, b1, 0,  0,  0,  0,  0],
            [0,  b6, 0,  b5, b4, 0,  b3, b2, b1, 0,  0,  0,  0,  0,  0],
            [0,  0,  0,  0,  b6, 0,  0,  b5, b4, 0,  0,  b3, b2, b1, 0 ] ];

time(d1d:=det_minor(d1));
time(d2d:=det_minor(d2));
time(d3d:=det_minor(d3));
time(g1:=gcd(eval(d1d,1), eval(d2d,1)));
time(g2:=gcd(eval(g1,1),eval(d3d,1)));
time(qqq:=factor(eval(g2,1)));