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

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

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

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

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

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

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

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

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

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

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

(8ab-zx)*(zx+8ab)=*()2-()2

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

(mlu+8k)*(8k-mlu)=*2-()2

(19bc3-8x)*(8x+19bc3)=*b2c6-*2

(19bc3-8x)*(8x+19bc3)=(*bc3)2-*2



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