Question

Find the coefficient of ${x}^{2} {y}^{2}$in the expansion of $( - 6x - y)^{4}$Give answer as an integer

Answer 1

Since the binomial is elevated to a even power, we have that:

$(-6x-y)^4=(6x+y)^4$

Now we need to remember The Binomial Theorem

We now apply the previous formula to our particular problem, obtaining: