Find (xy + y^{2})(2x + 9y).

Distribute (xy + y^{2}) over (2x + 9y) to find

(xy + y^{2})(2x) + (xy + y^{2})(9y)

Distribute further to get

(xy)(2x) + (y^{2})(2x) + (xy)(9y) + (y^{2})(9y)

and then simplify for

2x^{2}y + 2xy^{2} + 9xy^{2} + 9y^{3}

which can be combined further to give us

2x^{2}y + 11xy^{2} + 9y^{3}.