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a) 491 x (267+53) - 491 x ( 153 + 67 )
=491x<(267+53) - (153+67)>
=491x<300-200>
=491x100
=49100
b) 53 x 39 + 47 x 39 - 53 x 21 - 47 x 21
=53x(39-21) - 47x(39-21)
=53x18-47x18
=18x(53-47)
=18x6
=108
bạn ơi cho mình sửa phần b) nha
b) 53 x 39 + 47 x 39 - 53 x 21 - 47 x 21
=53x(39-21) + 47x(39-21)
=53x18+47x18
=18x(53+47)
=18x100
=1800
![](https://rs.olm.vn/images/avt/0.png?1311)
`47/53*(17/3-53/47)+17/3*(6/17-47/53)`
`=47/53*17/3-1+6/3-17/3*47/53`
`=2-1+17/3*47/53-17/3*47/53`
`=1`
\(\dfrac{47}{53}.\left(\dfrac{17}{3}-\dfrac{53}{47}\right)+\dfrac{17}{3}.\left(\dfrac{6}{17}-\dfrac{47}{53}\right)\)
\(=\dfrac{47}{53}.\dfrac{17}{3}-\dfrac{47}{53}.\dfrac{53}{47}+\dfrac{17}{3}.\dfrac{6}{17}-\dfrac{17}{3}.\dfrac{47}{53}\)
\(=\left(\dfrac{47}{53}.\dfrac{17}{3}-\dfrac{17}{3}.\dfrac{47}{53}\right)+\left(\dfrac{-47}{53}.\dfrac{53}{47}+\dfrac{17}{3}.\dfrac{6}{17}\right)\)
\(=\left(1-1\right)+\left(-1+2\right)\)
\(=0+1\)
\(=1\)
![](https://rs.olm.vn/images/avt/0.png?1311)
= 39 . ( 53 + 47 ) - 21 . ( 53 + 47 ) = 39 . 100 - 21 . 100 = 100 . ( 39 - 21 ) = 100 . 18 = 1800
![](https://rs.olm.vn/images/avt/0.png?1311)
\(53.39+47.39-53.21-47.21\)
\(=53\left(39-21\right)+47\left(39-21\right)\)
\(=\left(39-21\right)\left(53+47\right)\)
\(=18.100=1800\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(=\frac{47}{53}.\frac{17}{3}-\frac{47}{53}.\frac{53}{47}+\frac{17}{3}.\frac{6}{17}-\frac{17}{3}.\frac{47}{53}\)
\(=\left(\frac{47}{53}.\frac{17}{3}-\frac{17}{3}.\frac{47}{53}\right)+\left(\frac{47}{53}.\frac{53}{47}-\frac{17}{3}.\frac{6}{17}\right)\)
\(=0+\left(-1\right)\)
\(=-1\).
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\text{47-(-53)+(-47)-|-53|=47+53-47-53=(47-47)+(53-53)=0+0=0}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
= 47 . [(-153) - (-53)]
= 47 . (-100)
= -4700
47.(53-153)
47.(-100)
-4700