Question

How do you find the binomial expansion of the expression `(x+3y)^7`?

Answer 1

You use the binomial theorem which states

`(x+y)^n=sum_(k=0)^n(n/k)x^(n-k)y^k`

Explanation:

So by using the binomial theorem we have that

`(x+3y)^7=x^7+21x^6y+189x^5y^2+945x^4y^3+2835x^3y^4+5103x^2y^5+5103xy^5+2187y^7`