Answer:

Explanation:
we want to solve the following binomial:

There is a handy way to expand powers of binomials which is known as binomial theorem . and it describes the algebraic expansion of powers of a binomial. binomial theorem is given by

comparing (x+6)⁶ to (a+b)ⁿ , we get
now substitute them on the formula which yields:

converting the summation notation into sum yields:

and we're done!