a2-b2=(a-b)(a+b)
(1-x)*(1+x)=-2
(a-1)*(a+1)=2-
(1-cd)*(1+cd)=-()2
(8b-1)*(8b+1)=*2-
(8b-1)*(8b+1)=(*)2-
(6-m)*(6+m)=-2
(z-6)*(z+6)=2-
(6-cd)*(cd+6)=-()2
(1b-6)*(1b+6)=*2-
(1b-6)*(6+1b)=(*)2-
(8ab-zx)*(zx+8ab)=*()2-()2
(8z+a)*(a-8z)=2-*2
(mlu+8k)*(8k-mlu)=*2-()2
(6bc3-8x)*(8x+6bc3)=*b2c6-*2
(6bc3-8x)*(8x+6bc3)=(*bc3)2-*2