Consider the following question.
(x+y)(2x+3y)−(x+y)(x+1)=?
=(x)(2x)+(x)(3y)+(y)(2x)+(y)(3y)−x2−xy−x−y
=2x2+3xy+2xy+3y2−x2−xy−x−y
=x2+4xy+3y2−x−y
Hence, this is the required answer.
Factorise : (x+y)(2x+5)−(x+y)(x+3)