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

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

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

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

(7b-3)*(7b+3)=*2-

(7b-3)*(7b+3)=(*)2-

(18-m)*(18+m)=-2

(z-18)*(z+18)=2-

(18-cd)*(cd+18)=-()2

(3b-18)*(3b+18)=*2-

(3b-18)*(18+3b)=(*)2-

(7ab-zx)*(zx+7ab)=*()2-()2

(7z+a)*(a-7z)=2-*2

(mlu+7k)*(7k-mlu)=*2-()2

(18bc3-7x)*(7x+18bc3)=*b2c6-*2

(18bc3-7x)*(7x+18bc3)=(*bc3)2-*2


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