a2-b2=(a-b)(a+b)

(8-x)*(8+x)=-2

(a-8)*(a+8)=2-

(8-cd)*(8+cd)=-()2

(7b-8)*(7b+8)=*2-

(7b-8)*(7b+8)=(*)2-

(19-m)*(19+m)=-2

(z-19)*(z+19)=2-

(19-cd)*(cd+19)=-()2

(8b-19)*(8b+19)=*2-

(8b-19)*(19+8b)=(*)2-

(7ab-zx)*(zx+7ab)=*()2-()2

(7z+a)*(a-7z)=2-*2

(mlu+7k)*(7k-mlu)=*2-()2

(19bc3-7x)*(7x+19bc3)=*b2c6-*2

(19bc3-7x)*(7x+19bc3)=(*bc3)2-*2



×