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