Explanation:
Expand Using the Binomial Theorem (X+Y)^4 (X + Y)4 ( X + Y) 4 Use the binomial expansion theorem to find each term. The binomial theorem states (a+b)n = n ∑ k=0nCk⋅(an−kbk) ( a + b) n = ∑ k = 0 n n C k ⋅ ( a n - k b k). 4 ∑ k=0 4! (4− k)!k! ⋅(X)4−k ⋅(Y)k ∑ k = 0 4 4! ( 4 - k)! k! ⋅ ( X) 4 - k ⋅ ( Y) k Expand the summation. 4! (4−0)!0!