Let X₁ and X₂ be independent binomial random variables with Xᵢ having parameters (nᵢ, pᵢ), i = 1,2. Find
(a) P(X₁X₂ = 0) ;
(b) P(X₁ + X₂ = 1) ;
(c) P(X₁ + X₂)