a2-b2=(a-b)(a+b)
(5-x)*(5+x)=-2
(a-5)*(a+5)=2-
(5-cd)*(5+cd)=-()2
(4b-5)*(4b+5)=*2-
(4b-5)*(4b+5)=(*)2-
(8-m)*(8+m)=-2
(z-8)*(z+8)=2-
(8-cd)*(cd+8)=-()2
(5b-8)*(5b+8)=*2-
(5b-8)*(8+5b)=(*)2-
(4ab-zx)*(zx+4ab)=*()2-()2
(4z+a)*(a-4z)=2-*2
(mlu+4k)*(4k-mlu)=*2-()2
(8bc3-4x)*(4x+8bc3)=*b2c6-*2
(8bc3-4x)*(4x+8bc3)=(*bc3)2-*2