Question

9у²-25=
4а-а³=
-2а²+4ас-2с²=

Answer 1

$1)9y^2-25=(3y-5)(3y+5)$
$2)4a-a^3=a(4-a^2)=a(2-a)(2+a)$
$3)-2a^2+4ac-2c^2=-2(a^2-2ac+c^2)=-2(a-c)^2$