A cura di: Alfredo Bochicchio

$5a^2xy-20abxy+20b^2xy$
$5xy(a^2-4ab+4b^2)$
$5xy(a+2b)^2$
$20a^3+45ab^2-60a^2b$
$5a(4a^2+9b^2-12ab)$
$5a(2a+3b)^2$