a2-b2=(a-b)(a+b)
(2-x)*(2+x)=-
2
(a-2)*(a+2)=2-
(2-cd)*(2+cd)=-(
)2
(2b-2)*(2b+2)=*
2-
(2b-2)*(2b+2)=(*
)2-
(16-m)*(16+m)=-
2
(z-16)*(z+16)=2-
(16-cd)*(cd+16)=-(
)2
(2b-16)*(2b+16)=*
2-
(2b-16)*(16+2b)=(*
)2-
(2ab-zx)*(zx+2ab)=*(
)2-(
)2
(2z+a)*(a-2z)=2-
*
2
(mlu+2k)*(2k-mlu)=*
2-(
)2
(16bc3-2x)*(2x+16bc3)=*b2c6-
*
2
(16bc3-2x)*(2x+16bc3)=(*bc3)2-
*
2