Connection to Pascal's Triangle

(x+y)0
=
1
(x+y)1
=
1x+1y
(x+y)2
=
1x2+2xy+1y2
(x+y)3
=
1x3+3x2y+3xy2+1y3
(x+y)4
=
1x4+4x3y+6x2y2+4xy3+1y4
(x+y)5
=
1x5+5x4y+10x3y2+10x2y3+5xy4+1y5

Do you see the connection??