Question

2xy-x^2-y^2-16

Answer 1

   2xy - x² - y² - 16

= - ( x² - 2xy + y² ) - 16

= - ( x - y )² - 4²

= ( x + y - 4 )( x + y + 4 )

Answer 2

\(2xy-x^2-y^2-16.\)

\(=-\left(x^2-2xy+y^2+16\right)\)

\(=-\left[\left(x-y\right)^2+16\right]\)

\(=-\left(x-y\right)^2-16\)

=> đưa HĐT