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\(2019+2019+2019+2019+2019x7-2019\)
\(=2019x\left(7+4-1\right)\)
\(=2019x10=20190\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) (4+4)x(2019 +2019 +.....+2019)
= 8 x 125 x 2019
= (8 x 125) x 2019
= 1000 x 2019
= 2019000
b) ( 42+42+...+42)+(125+125+....+125)
= 42 x 125 + 58 x 125
= 125 x ( 42 + 58)
= 125 x 100
= 12500
42+42+...+42)+(125+125+....+125)
= 42 x 125 + 58 x 125
= 125 x ( 42 + 58)
= 125 x 100
= 12500
![](https://rs.olm.vn/images/avt/0.png?1311)
Tính bằng cách thuận tiện nhất.
2019 + 2019 +2019 + 2019 + 2019 x 7 - 2019
= 2019 x ( 7 +1 +1+1 - 1 ) = 2019 x 10 = 20190
![](https://rs.olm.vn/images/avt/0.png?1311)
2019 + 2019 + 2019 + 2019 + 2019 . ( 7-2019 )
= 2019 . 5 . ( -2012 )
= - 20311140
Học tốt
![](https://rs.olm.vn/images/avt/0.png?1311)
\(B=\frac{1}{2019}+\frac{2}{2019}+\frac{3}{2019}+...+\frac{2019}{2019}\)
\(=\frac{1+2+3+...+2019}{2019}\)
\(=\frac{\left(2019+1\right).\left[\left(2019-1\right)+1\right]:2}{2019}\)
\(=\frac{2039190}{2019}\)
\(=1010\)
![](https://rs.olm.vn/images/avt/0.png?1311)
2019 x 45 + 54 x 2019 + 2019/2019 x 2022 - 2018 x 201
=2019*(45+54+1)-2018
=2019*100-2018
=201900-2018
=199882
2019 x 45 + 54 x 2019 + 2019/2019 x 2022 - 2018 x 201
=2019*(45+54+1)-2018
=2019*100-2018
=201900-2018
=199882
![](https://rs.olm.vn/images/avt/0.png?1311)
\(2019+2019+2019+2019+2019\times7-2019\\ =2019\times\left(1+1+1+1+7-1\right)\\ =2019\times10\\ =20190\)
Tính bằng cách thuận tiện nhất.
2019 + 2019 +2019 + 2019 + 2019 x 7 - 2019
= 2019 x ( 7 +1 +1+1 - 1 ) = 2019 x 10 = 20190