①(m+4)^2-(m+4)(n+4) =(m+4)*(m+4-n-4)==(m+4)*(m-n)
②x^2-9y^2+2x-6y=(x^2+2x+1)-(9y²+6y+1)=(x+1)²-(3y+1)²=(x-3y)*(x+3y+2)
③x^2 y^2 -x^2 -y^2 +1=x^2 (y^2 -1)-(y^2 -1)=(y^2 -1)*(x^2-1)=(x+1)(x-1)(y+1)(y-1)
①(m+4)^2-(m+4)(n+4) =(m+4)*(m+4-n-4)==(m+4)*(m-n)
②x^2-9y^2+2x-6y=(x^2+2x+1)-(9y²+6y+1)=(x+1)²-(3y+1)²=(x-3y)*(x+3y+2)
③x^2 y^2 -x^2 -y^2 +1=x^2 (y^2 -1)-(y^2 -1)=(y^2 -1)*(x^2-1)=(x+1)(x-1)(y+1)(y-1)