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

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

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

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

(6b-9)*(6b+9)=*2-

(6b-9)*(6b+9)=(*)2-

(16-m)*(16+m)=-2

(z-16)*(z+16)=2-

(16-cd)*(cd+16)=-()2

(9b-16)*(9b+16)=*2-

(9b-16)*(16+9b)=(*)2-

(6ab-zx)*(zx+6ab)=*()2-()2

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

(mlu+6k)*(6k-mlu)=*2-()2

(16bc3-6x)*(6x+16bc3)=*b2c6-*2

(16bc3-6x)*(6x+16bc3)=(*bc3)2-*2


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