(a+3)•(a-3)=3а•(-2а)=-6a
(5+d)•(5-d)=5d•4d=20d
(x+1)•(1-x)=x•x=x
(2a+b)•(2a-b)=(2a+2a)•(b-b)=4a•b
(a-3b)•(3b+a)=(3b-3b)•(a+a)=b•2a
(2m-3n)•(2m+3n)=(2m+2m)•(3n-3n)=4m•n
(a+3)•(a-3)=3а•(-2а)=-6a
(5+d)•(5-d)=5d•4d=20d
(x+1)•(1-x)=x•x=x
(2a+b)•(2a-b)=(2a+2a)•(b-b)=4a•b
(a-3b)•(3b+a)=(3b-3b)•(a+a)=b•2a
(2m-3n)•(2m+3n)=(2m+2m)•(3n-3n)=4m•n