formulario prodotti notevoli

$(a+b{)}^2=a^2+2ab+b^2$
$(a-b{)}^2=a^2-2ab+b^2$
$(a+b{)}^3=a^3+3a^{2}b+3a{b}^2+b^3$
$(a-b{)}^3=a^3-3a^{2}b+3a{b}^2-b^3$
$a^2-b^2=(a+b)(a-b)$
$a^3+b^3=(a+b)(a^2-ab+b^2)$
$a^3-b^3=(a-b)(a^2+ab+b^2)$
$(a+b+c{)}^2=a^2+b^2+c^2+2ab+2bc+2ac$
$(a-b+c{)}^2=a^2+b^2+c^2-2ab+2bc-2ac$
$(a+b{)}^n=\sum _{k=0}^n(\genfrac{}{}{0ex}{}{n}{k})a^{n-k}{b}^k$