a2-b2=(a-b)(a+b)
(8-x)*(8+x)=-2
(a-8)*(a+8)=2-
(8-cd)*(8+cd)=-()2
(4b-8)*(4b+8)=*2-
(4b-8)*(4b+8)=(*)2-
(16-m)*(16+m)=-2
(z-16)*(z+16)=2-
(16-cd)*(cd+16)=-()2
(8b-16)*(8b+16)=*2-
(8b-16)*(16+8b)=(*)2-
(4ab-zx)*(zx+4ab)=*()2-()2
(4z+a)*(a-4z)=2-*2
(mlu+4k)*(4k-mlu)=*2-()2
(16bc3-4x)*(4x+16bc3)=*b2c6-*2
(16bc3-4x)*(4x+16bc3)=(*bc3)2-*2