Factorise 9x+9y+x2+xy completely.

Sure, let's factorise the given expression step by step:

The given expression is 9x + 9y + x^2 + xy.

Step 1: Rearrange the terms to group like terms together. This gives us:

x^2 + xy + 9x + 9y.

Step 2: Factor by grouping. This involves factoring out the greatest common factor (GCF) from each group:

x(x + y) + 9(x + y).

Step 3: Notice that (x + y) is a common factor. Factor this out to get the final factorised form:

(x + 9)(x + y).

So, the factorised form of 9x + 9y + x^2 + xy is (x + 9)(x + y).