ĐÁP ÁN B. ( ) ( )2 2 2 . ( )2 2M = X + Y = X + X Y + Y = +X XY...
Câu 29. Đáp án B.
( ) ( )
2
2
2 .( )
2
2M = x + y = x + x y + y = +x xy +y( ) ( ) (
x3
y3
x y x)(
xy y)
- - + += - = = = + +x x y yN x xy y- - -x y x y x y( )( ) ( ) ( )
2
2
P = x - y x + y = x - y = -x y Vậy N = +x xy +y.