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![](https://rs.olm.vn/images/avt/0.png?1311)
\(\dfrac{5}{3}\cdot\dfrac{7}{25}+\dfrac{5}{3}\cdot\dfrac{21}{25}-\dfrac{5}{3}\cdot\dfrac{7}{25}\)
\(=\dfrac{5}{3}\cdot\left(\dfrac{7.}{25}+\dfrac{21}{25}-\dfrac{7}{25}\right)\)
\(=\dfrac{5}{3}\cdot\dfrac{21}{25}=\dfrac{7}{5}\)
b) \(250\%+19\dfrac{3}{11}\cdot\dfrac{7}{26}-6\dfrac{3}{11}\cdot\dfrac{7}{26}\)
\(=\dfrac{5}{2}+\dfrac{212}{11}\cdot\dfrac{7}{26}-\dfrac{69}{11}\cdot\dfrac{7}{26}\)
\(=\dfrac{7}{26}\cdot\left(\dfrac{212}{11}-\dfrac{69}{11}\right)+\dfrac{5}{2}\)
\(=\dfrac{7}{26}\cdot13+\dfrac{5}{2}\)
\(=\dfrac{7}{2}+\dfrac{5}{2}\)
\(=\dfrac{12}{2}=6\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a,
11+6+(-11)+(-3)
= [11+(-11)]+(6+(-3)]
=0+3
=3
b,
25.7.(-5).(-4).2
=[25.(-4)].[-5.(-2)].7
=-100.10.7
-7000
c,
3.25-7.(-25)
=3.25+7.25
=(3+7).25
=10.250
=250
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) 2/9 - (1/20 + 2/9)
= 2/9 - 1/20 - 2/9
= (2/9 - 2/9) - 1/20
= 0 - 1/20
= -1/20
b) -3/14 + 2/13 + (-25/14) + (-15/13)
= (-3/14 - 25/14) + (2/13 - 15/13)
= -2 - 1
= -3
c) -3/11 + 11/8 - 3/8 + (-8/11)
= (-3/11 - 8/11) + (11/8 - 3/8)
= -1 + 1
= 0
d) 3/8 + (-1/4) - (7/12 - 1/6)
= 1/8 - 5/12
= -7/24
e) (1/3 + 12/67 + 13/41) - (79/67 - 28/41)
= 1/3 + 12/67 + 13/41 - 79/67 + 28/41
= 1/3 + (12/67 - 79/67) + (13/41 + 28/41)
= 1/3 - 1 + 1
= 1/3
![](https://rs.olm.vn/images/avt/0.png?1311)
(259.11 - 252.257) : 258
= (259.11 - 259) : 258
= 259.(11 - 1) : 258
= 25.10
= 250
\(\left(25^9.11-25^2.25^7\right):28\)
\(=\left(25^9.11-25^9\right):25^8\)
\(=\left[25^9\left(11-1\right)\right]:25^8\)
\(=\left(25^9.10\right):25^8\)
\(=25^9:25^8.10\)
\(=25.10\)
\(=250\)
Ta có :
11 . ( 7 - 25 ) + 7. ( 25 - 11 )
= 11 . 7 - 11 . 25 + 7 . 25 - 7 . 11
= ( 11 . 7 - 7 . 11 ) + ( -11 . 25 + 7 . 25 )
= 0 + [ ( -11 ) + 7 ] . 25
= 0 + 4 . 25
= 0 + 100
= 100
Tham khảo nha !!!
Sửa lại nha
-11 + 7 = -4
-4 .25 = -100
Đáp án : -100