(x+2)*(x+5)=0
(x+2)^2-(x+5)^2=0
(x+2+x+5)(x+2-x-5)=0
-3(2x+7)=0
2x+7=0
x=-7/2
(m+n)*(m-n)
=(m+n)^2-(m-n)^2
=(m+n+m-n)(m+n-m+n)
=4mn
(x+2)*(x+5)=0
(x+2)^2-(x+5)^2=0
(x+2+x+5)(x+2-x-5)=0
-3(2x+7)=0
2x+7=0
x=-7/2
(m+n)*(m-n)
=(m+n)^2-(m-n)^2
=(m+n+m-n)(m+n-m+n)
=4mn