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

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

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

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

(3b-1)*(3b+1)=*2-

(3b-1)*(3b+1)=(*)2-

(3-m)*(3+m)=-2

(z-3)*(z+3)=2-

(3-cd)*(cd+3)=-()2

(1b-3)*(1b+3)=*2-

(1b-3)*(3+1b)=(*)2-

(3ab-zx)*(zx+3ab)=*()2-()2

(3z+a)*(a-3z)=2-*2

(mlu+3k)*(3k-mlu)=*2-()2

(3bc3-3x)*(3x+3bc3)=*b2c6-*2

(3bc3-3x)*(3x+3bc3)=(*bc3)2-*2



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