Step 11: The coefficient of x^4 in the expansion is 2160.
Binomial Theorem – The Binomial Theorem is used to expand expressions of the form (a + b)^n, where the coefficients can be calculated using combinations.
Combination Formula – The combination formula C(n, k) = n! / (k!(n-k)!) is used to determine the number of ways to choose k elements from a set of n elements.
Power of a Product – When raising a product to a power, each factor in the product is raised to that power.