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

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

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

(7-cd)*(7+cd)=-()2

(8b-7)*(8b+7)=*2-

(8b-7)*(8b+7)=(*)2-

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

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

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

(7b-1)*(7b+1)=*2-

(7b-1)*(1+7b)=(*)2-

(8ab-zx)*(zx+8ab)=*()2-()2

(8z+a)*(a-8z)=2-*2

(mlu+8k)*(8k-mlu)=*2-()2

(1bc3-8x)*(8x+1bc3)=*b2c6-*2

(1bc3-8x)*(8x+1bc3)=(*bc3)2-*2


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