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![](https://rs.olm.vn/images/avt/0.png?1311)
a.384:25:4=384:[25x4]=384:100=3.84
380:[38x2]=[380:38]x2=20
![](https://rs.olm.vn/images/avt/0.png?1311)
a) 384 : 25 : 4 = 384 : ( 25 x 4 ) = 384 : 100 = 3,84
b) 380 : ( 38 x 2 ) = ( 380 : 38 ) : 2 = 10 : 2 = 5
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có : 384 : 25 : 4= 384 : 25:4*4:4=384:25*4:4:4=384:100=3,84
\(\frac{37}{25}:\frac{5}{4}:\frac{74}{25}=\frac{37}{25}\cdot\frac{25}{74}:\frac{5}{4}=\frac{37}{74}:\frac{5}{4}=\frac{1}{2}:\frac{5}{4}=\frac{1}{2}\cdot\frac{4}{5}=\frac{2}{5}\)
\(\frac{6}{11}:\frac{4}{3}:\frac{5}{11}:\frac{4}{3}=\frac{6}{11}\cdot\frac{11}{5}:\frac{4}{3}:\frac{4}{3}=\frac{6}{5}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a)
4 x 64,3 x 2,5 = 64,3 x (2,5 x 4) = 64,3 x 10 = 643
b)
18,7 x 4,3 + 18,7 x 5,7 = 18,7(4,3 + 5,7) = 18,7 x 10 = 187
c)
25/141 x 17/11 - 25/141 x 6/11 = 25/141 x (17/11 - 6/11) = 25/141 x 11/11 = 25/141 x 1 = 25/141
d)
số số hạng trong dãy : 2006-1+1 =2006(số)
1+2+3+4+...+2006 = (2006+1)+(2005+2)+(2004+3)+....+(1003+1004)
số cặp có tổng bằng 2007 là : 2006 : 2 = 1003(cặp)
Vậy 1+2+3+4+.....+2006 = 1003 x 2007 = 2013021
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{2}{3}.\frac{4}{5}+\frac{1}{3}.\frac{4}{5}=\frac{4}{5}\left(\frac{2}{3}+\frac{1}{3}\right)=\frac{4}{5}.\frac{3}{3}=\frac{4}{5}.1=\frac{4}{5}\)
\(\frac{1}{2}:\frac{3}{4}+\frac{1}{6}:\frac{3}{4}=\frac{3}{4}:\left(\frac{1}{2}+\frac{1}{6}\right)=\frac{3}{4}:\frac{2}{3}=\frac{9}{8}\)
\(\frac{2}{3}.\frac{4}{5}-\frac{1}{3}.\frac{4}{5}=\frac{4}{5}\left(\frac{2}{3}-\frac{1}{3}\right)=\frac{4}{5}.\frac{1}{3}=\frac{4}{15}\)
\(\frac{1}{2}:\frac{3}{4}-\frac{1}{6}:\frac{3}{4}=\frac{3}{4}:\left(\frac{1}{2}-\frac{1}{6}\right)=\frac{3}{4}:\frac{1}{3}=\frac{9}{4}\)
\(\frac{2}{3}.\frac{4}{5}+\frac{1}{3}.\frac{4}{5}=\left(\frac{2}{3}+\frac{1}{3}\right).\frac{4}{5}=1.\frac{4}{5}=\frac{4}{5}\)
\(\frac{1}{2}:\frac{3}{4}+\frac{1}{6}:\frac{3}{4}=\frac{1}{2}.\frac{4}{3}+\frac{1}{6}.\frac{4}{3}=\left(\frac{1}{2}+\frac{1}{6}\right).\frac{4}{3}=\frac{2}{3}.\frac{4}{3}=\frac{8}{9}\)
c,d tương tự
![](https://rs.olm.vn/images/avt/0.png?1311)
a)\(\frac{21}{11}x\frac{22}{17}x\frac{68}{63}\)
=\(\frac{21x22x68}{11x17x63}\)
=\(\frac{21x11x2x17x4}{11x17x21x3}\)
=\(\frac{2x4}{3}\)
=\(\frac{8}{3}\)
b)\(\frac{5}{14}x\frac{7}{13}x\frac{26}{25}\)
=\(\frac{5x7x26}{14x13x25}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(\frac{8}{11}-\frac{28}{99}-\frac{14}{99}=\frac{72}{99}-\frac{28}{99}-\frac{14}{99}=\frac{30}{99}=\frac{10}{33}\)
b) \(5\frac{3}{4}-3\frac{1}{2}=\)\(\frac{23}{4}-\frac{7}{2}=\frac{23}{4}-\frac{14}{4}=\frac{9}{4}\)
A) 8/11- 28/99- 14/99 8/11=72/99 (72/99 +28/99)-14/99 =100/99-14/99 =86/99
a)=384:(25*4)=384:100=3,84.
b)37/25:5/4:74/25=37/25*4/5*25/74=37*4*25/5*25*74=2/5.
c)380:(38*2)=(380:38):2=10:2=5.
d)6/11:4/3:5/11:4/3=6/11*3/4*11/5*3/4=6*3*11*3/11*4*5*4=27/40.
k nha
a,384:25:4
=15.36:4
=3.84