a/ (-8) x 25 x (-2) x 4 x (-5) x 125
= [(-8) x 125) x (25 x 4) x [(-2) x (-5)]
= (-1000) x 100 x 10
= -1000000
b/ (a + b) x (1 + X + y)
= (a + b) x 1 + (a + b) x X + (a + b) x y
= a x 1 + b x 1 + a x X + b X x + a x y + b x y
= a + b + a x X + b x X + a x y + b x y
ủng hộ mk nha !!!