added poly x poly + horner

gallery/example4.typ

@@ -32,3 +32,16 @@ $
   [quotient: #poly.display(div.quotient)],
   [rest: #poly.display(div.rest)],
 ))
+
+#let r = poly.poly(6, -11, 6, -1)
+#let horner = poly.horner(r, 2)
+$
+  r = #poly.display(r, var: "lambda") =
+  (#poly.display(horner.root-factor, var: "lambda"))
+  (#poly.display(horner.factor, var: "lambda"))
+$
+
+#(horner.display)()
+
+#let a = poly.mul(horner.root-factor, horner.factor)
+$#poly.display(a, var: "lambda")$