Maths help Factorise (a+b) + a +b?

(a + b)^2 + a + b
= (a + b)^2 + (a + b)

Let a + b = y.
(a + b)^2 + (a + b)
= y^2 + y
= y(y + 1)

Change y into a + b:
y(y + 1)
= [a + b][(a + b) + 1]
= [a + b][a + b + 1]

(a + b)² + (a + b)
(a + b) [ (a + b) + 1 ]

(a+b)^2+a+b
=a^2+b^2+2ab+a+b

(a+b)^2+a+b=
(a+b)(a+b+1)