3. For G₁ and G₂ finite groups and V₁, V₂ finite dimensional complex representations of G₁, G₂ respectively, the tensor product V₁ ⊗ V₂ is given an action of G₁ × G₂ by
$$(g_1, g_2).(v_1 \otimes v_2) = (g_1.v_1) \otimes (g_2.v_2).$$
(a) Show that this is a representation.
(b) Calculate its character in terms of χv₁ and χv₂.
(c) If V₁, V₂ are irreducible, show that V₁ ⊗ V₂ is irreducible.
(d) Show that all irreducible representations of G₁ × G₂ arise this way.