A) X2 + XY –X – Y = X(X + Y) – (X + Y) = (X + Y)(X -1 ).B) A2 – B...

Bài 1a) x

²

+ xy –x – y = x(x + y) – (x + y) = (x + y)(x -1 ).b) a

²

– b

²

+ 8a + 16 = (a

²

+ 8a + 16) – b

²

= (a + 4)

²

– b

²

= (a + 4 – b)(a + 4 + b).