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![](https://rs.olm.vn/images/avt/0.png?1311)
a)
(1/3-1/5)x1/4 = 1/3x1/4-1/5x1/4=1/12-1/20=1/30
(1/3-1/5)x1/4 = 2/15x1/4=1/30
b)
2/5 x 3/7 + 2/5 x 4/7= 6/35 + 8/35 = 14/35 = 2/5
2/5 x 3/7 + 2/5 x 4/7= (3/7+4/7) x 2/5 = 1 x 2/5 = 2/5
![](https://rs.olm.vn/images/avt/0.png?1311)
a: C1: (1/3-1/5)*1/4
=2/15*1/4=2/60=1/30
C2: (1/3-1/5)*1/4
=1/3*1/4-1/5*1/4
=1/12-1/20=1/30
b: C1: 2/5*3/7+2/5*4/7
=6/35+8/35=14/35=2/5
C2: 2/5*3/7+2/5*4/7
=2/5(3/7+4/7)
=2/5*1=2/5
![](https://rs.olm.vn/images/avt/0.png?1311)
a. \(\dfrac{656565}{272727}=\dfrac{65}{27}\)
b. \(\dfrac{2}{7}\left(\dfrac{3}{4}+\dfrac{9}{4}\right)=\dfrac{6}{7}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
1,
a, \(x\)x 124= 4829-365
\(x\)x 124 = 4464
\(x\)= 4464 :124
\(x\)= 36.
b,\(x\)x 137 = 25 x 3
\(x\)x 137 = 75
\(x\)= \(\frac{75}{137}\)
2,
\(\frac{4}{5}\)x\(\frac{3}{7}+\frac{4}{5}\)x\(\frac{6}{7}-\frac{4}{5}\)x\(\frac{4}{10}\)
=\(\frac{4}{5}\)x\(\left(\frac{3}{7}+\frac{6}{7}-\frac{4}{10}\right)\)=\(\frac{4}{5}\)x\(\frac{31}{35}\)\(\frac{124}{175}\)
\(\text{Bài }1\text{ : Tìm }x\text{ : }\)
\(a,\text{ }x\text{ x }124=4829-365\)
\(x\text{ x }124=4464\)
\(x=4464\text{ : }124\)
\(x=36\)
\(b,\text{ }x\text{ x }137=25\text{ x }3\)
\(x\text{ x }137=75\)
\(x=75\text{ : }137\)
\(x=\frac{75}{137}\)
\(\text{Bài }2\text{ : Tính bằng cách thuận tiện nhất : }\)
\(\frac{4}{5}\text{ x }\frac{3}{7}+\frac{4}{5}\text{ x }\frac{6}{7}-\frac{4}{5}\text{ x }\frac{4}{10}\)
\(=\frac{4}{5}\text{ x }\left(\frac{3}{7}+\frac{6}{7}-\frac{4}{10}\right)\)
\(=\frac{4}{5}\text{ x }\left(\frac{9}{7}-\frac{4}{10}\right)\)
\(=\frac{4}{5}\text{ x }\frac{31}{35}\)
\(=\frac{124}{175}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Mình đưa 1/2 về thành 0,5, mình nói để bạn hiểu nhé.
0,5 x 46,24 + 1/2 x 53,76 + 1/4 x 3,8
= 0,5 x ( 46,24 + 53,76 ) + 1/4 x 3,8
=0,5 x 100 + 1/4 x 3,8
= 50 + 0,95 = 50,95.
Chúc bạn học tốt ~<>
=0,5x46,24+0,5x53,76+0,95
=0,5x(46,24+53,76)+0,95
=0,5x100+0,95
=50+0,95
=50,95
![](https://rs.olm.vn/images/avt/0.png?1311)
\(1-\frac{1}{3}-\frac{1}{9}=\frac{9}{9}-\frac{3}{9}-\frac{1}{9}=\frac{9-3-1}{9}=\frac{5}{9}\)
(1256 + 859 + 5864 - 2568) x (3 x 672 -7 x 288)
=5411x(2016-2016)
=5411x0
( 1256 + 859 + 5864 - 2568 ) x ( 3 x 672 - 7 x 288 )
= 5411 x (2016 - 2016)
= 5411 x 0
= 0
~~~~~~~~~~~~~~~~~~~~~~hok tot~~~~~~~~~~~~~~~~~~~