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

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

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

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

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

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

(9-m)*(9+m)=-2

(z-9)*(z+9)=2-

(9-cd)*(cd+9)=-()2

(3b-9)*(3b+9)=*2-

(3b-9)*(9+3b)=(*)2-

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

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

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

(9bc3-2x)*(2x+9bc3)=*b2c6-*2

(9bc3-2x)*(2x+9bc3)=(*bc3)2-*2



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