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

(1-x)*(1+x)=-2

(a-1)*(a+1)=2-

(1-cd)*(1+cd)=-()2

(1b-1)*(1b+1)=*2-

(1b-1)*(1b+1)=(*)2-

(4-m)*(4+m)=-2

(z-4)*(z+4)=2-

(4-cd)*(cd+4)=-()2

(1b-4)*(1b+4)=*2-

(1b-4)*(4+1b)=(*)2-

(1ab-zx)*(zx+1ab)=*()2-()2

(1z+a)*(a-1z)=2-*2

(mlu+1k)*(1k-mlu)=*2-()2

(4bc3-1x)*(1x+4bc3)=*b2c6-*2

(4bc3-1x)*(1x+4bc3)=(*bc3)2-*2



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