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

(6-x)*(6+x)=-2

(a-6)*(a+6)=2-

(6-cd)*(6+cd)=-()2

(2b-6)*(2b+6)=*2-

(2b-6)*(2b+6)=(*)2-

(15-m)*(15+m)=-2

(z-15)*(z+15)=2-

(15-cd)*(cd+15)=-()2

(6b-15)*(6b+15)=*2-

(6b-15)*(15+6b)=(*)2-

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

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

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

(15bc3-2x)*(2x+15bc3)=*b2c6-*2

(15bc3-2x)*(2x+15bc3)=(*bc3)2-*2



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