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

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

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

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

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

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

(17-m)*(17+m)=-2

(z-17)*(z+17)=2-

(17-cd)*(cd+17)=-()2

(1b-17)*(1b+17)=*2-

(1b-17)*(17+1b)=(*)2-

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

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

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

(17bc3-2x)*(2x+17bc3)=*b2c6-*2

(17bc3-2x)*(2x+17bc3)=(*bc3)2-*2


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