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

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

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

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

(9b-5)*(9b+5)=*2-

(9b-5)*(9b+5)=(*)2-

(19-m)*(19+m)=-2

(z-19)*(z+19)=2-

(19-cd)*(cd+19)=-()2

(5b-19)*(5b+19)=*2-

(5b-19)*(19+5b)=(*)2-

(9ab-zx)*(zx+9ab)=*()2-()2

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

(mlu+9k)*(9k-mlu)=*2-()2

(19bc3-9x)*(9x+19bc3)=*b2c6-*2

(19bc3-9x)*(9x+19bc3)=(*bc3)2-*2


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