1. а) x^3-xy^2-6y^2+6x^2=х^2(х+6)-у^2(х+6)=(х+6)(х^2-у^2)=(х+6)(х+у)(х-у)
3. (а^2+4)^2-16а^2=(а+2)^2(а-2)^2
(а^2+4-4а)(а^2+4+4а)= (а+2)^2(а-2)^2
(а^2-2)^2(а^2+2)^2= (а+2)^2(а-2)^2
(4а+1)^2(4а-1)^2=(16а^2+1)^2-64а^2
(4а+1)^2(4а-1)^2=(16а^2+1-8а)(16а^2+1+8а)
(4а+1)^2(4а-1)^2=(4а-1)^2(4а+1)^2
