#### Answer

$x^6+6x^5y+15x^4y^2+20x^3y^3+15x^2y^4+6xy^5+y^6$

#### Work Step by Step

$(x+y)^n=\binom{n}{0}x^ny^0+\binom{n}{1}x^{n-1}y^1+...+\binom{n}{a}x^{n-a}y^a+..\binom{n}{n}x^{0}y^n$
Here: $n=6$,
$(x+y)^6=\binom{6}{0}x^6y^0+\binom{6}{1}x^{6-1}y^1+\binom{6}{2}x^{6-2}y^2+\binom{6}{3}x^{6-3}y^3+\binom{6}{4}x^{6-4}y^4+\binom{6}{5}x^{6-5}y^5+\binom{6}{6}x^{6-6}y^6=$
$x^6+6x^5y+15x^4y^2+20x^3y^3+15x^2y^4+6xy^5+y^6$