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

(5-x)*(5+x)=-2

(a-5)*(a+5)=2-

(5-cd)*(5+cd)=-()2

(2b-5)*(2b+5)=*2-

(2b-5)*(2b+5)=(*)2-

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

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

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

(5b-7)*(5b+7)=*2-

(5b-7)*(7+5b)=(*)2-

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

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

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

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

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


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