Answer:
3(a +3)
Step-by-step explanation:
(a+3)^2 -a(a+3)
FOIL
a^2 +3a+3a+9 -a(a+3)
Distribute
a^2 +3a +3a +9 -a^2 -3a
Combine like terms
3a +9
FACTOR out a+3
(a+3)( a+3 -a)
(a+3) (3)
3(a+3)
Expand the first set of brackets first
(a+3)^2
A^2 + 3a + 3a +9
=A^2 + 6a + 9
Expand the second set of brackets
-a(a+3)
=-a^2 - 3a
Add both sets together
3a + 9
Factorise:
