= 2021 . ( -1990 - 72 ) - 2021 . ( 28 - 1990 )
= 2021 . ( - 1990 - 72 - 28 + 1990 )
= 2021 . -100 = - 202100
tham khảo ạ
= 2021 . ( -1990 - 72 ) - 2021 . ( 28 - 1990 )
= 2021 . ( - 1990 - 72 - 28 + 1990 )
= 2021 . -100 = - 202100
\(2021.\left(-1990-72\right)+\left(-2021\right).\left(28-1990\right)\\ =2021.\left(-1990-72\right)+2021.\left(-1\right).\left(28-1990\right)\\ =2021.\left(-1990-72\right)+2021.\left(-28+1990\right)\\ =2021.\left[\left(-1990+1990\right)+\left(-72-28\right)\right]\\ =2021.\left(0-100\right)\\ =2021.\left(-100\right)\\ =-202100\)
2021 . (-1990 - 72) + (-2021) . (28 - 1990)
= 2021 . (-1990 - 72) - 2021 . (28 - 1990)
= 2021 . [-1990 - 72 - (28 - 1990)]
= 2021 . (-1990 - 72 - 28 + 1990)
= 2021 . [(-1990 + 1990) - (72 + 28)]
= 2021 . (0 - 100)
= 2021 . (-100)
= -202100