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

(3-x)*(3+x)=-2

(a-3)*(a+3)=2-

(3-cd)*(3+cd)=-()2

(5b-3)*(5b+3)=*2-

(5b-3)*(5b+3)=(*)2-

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

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

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

(3b-7)*(3b+7)=*2-

(3b-7)*(7+3b)=(*)2-

(5ab-zx)*(zx+5ab)=*()2-()2

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

(mlu+5k)*(5k-mlu)=*2-()2

(7bc3-5x)*(5x+7bc3)=*b2c6-*2

(7bc3-5x)*(5x+7bc3)=(*bc3)2-*2


×