+ e = ex("(16+x^2*z^3)*(-17+3*x-5*z)*(2*x+3*z)*(x-y^2-z^3)", syms);
+ result += check_factor(e);
+
+ e = ex("(x-y*z)*(x-y^2-z^3)*(x+y+z)", syms);
+ result += check_factor(e);
+
+ e = ex("-(y^2-x+z^3)*x*(x+y+z)", syms);
+ result += check_factor(e);
+
+ e = ex("-316*(3*x-4*z)*(2*x+3*z)*(x+y)*(-1+x)", syms);
+ result += check_factor(e);
+
+ e = ex("(x+x^3+z^2)*(3*x-4*z)", syms);
+ result += check_factor(e);
+
+ e = ex("250*(-3+x)*(4*z-3*x)*(x^3+z^2+x)*x", syms);
+ result += check_factor(e);
+
+ e = ex("327*(x+z^2+x^3)*(3*x-4*z)*(-7+5*x-x^3)*(1+x+x^2)", syms);
+ result += check_factor(e);
+
+ e = ex("x-y^2-z^3", syms);
+ result += check_factor(e);
+
+ e = ex("-390*(7+3*x^4)*(2+x^2)*(x-z^3-y^2)", syms);
+ result += check_factor(e);
+
+ e = ex("55*(1+x)^2*(3*x-4*z)*(1+x+x^2)*(x+x^3+z^2)", syms);
+ result += check_factor(e);
+
+ e = ex("x+y*x-1", syms);
+ result += check_factor(e);
+
+ e = ex("390*(-1+x^6-x)*(7+3*x^4)*(2+x^2)*(y+x)*(-1+y-x^2)*(1+x^2+x)^2", syms);
+ result += check_factor(e);
+
+ e = ex("310*(y+x)*(-1+y-x^2)", syms);
+ result += check_factor(e);
+
+ return result;
+}
+
+static unsigned exam_factor3()
+{
+ unsigned result = 0;
+ ex e;
+ symbol k("k"), n("n");
+ lst syms;
+ syms = k, n;
+
+ e = ex("1/2*(-3+3*k-n)*(-2+3*k-n)*(-1+3*k-n)", syms);
+ result += check_factor(e);
+
+ e = ex("1/4*(2*k-n)*(-1+2*k-n)", syms);
+ result += check_factor(e);
+