Question

bài 1 tính nhanh24. (56-45) +56.(- 24-45)

Answer 1

24.(56-45)+56.(-24-45)

= 24.56-24.45-56.24-56.45

= (24.56-56.24)-(24.45+56.45)

= 0-45.(24+56)

= -45.80

= -3600

Answer 2

 24 . (56 - 45) + 56(-24 - 45)

= 24 . 56 - 24 . 45 + 56 . (-24) - 56 . 45

= [24 . 56 + 56 . (-24)] - (24 . 45 + 56 . 45)

= 56 . [24 + (-24)] - 45(24 + 56)

= 56 . 0 - 45 . 80 = 0 - 3600 = -3600