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\(\frac{13}{19}\times\left(\frac{19}{13}-\frac{7}{9}\right)\\ =\frac{13}{19}\times\frac{19}{13}-\frac{13}{19}\times\frac{7}{9}\)
\(=1-\frac{91}{171}\)
\(=\frac{80}{171}\)
Thấy đúng thì k đúng giúp mik
![](https://rs.olm.vn/images/avt/0.png?1311)
19/37+1-19/37
=(19/37-19/37)+1
=0+1
=1
9/8-(17/7-3/7)+7/8
=(9/8+7/8)-(17/7-3/7)
=2-2
=0
1/2+3/4+1/2
=(1/2+1/2)+3/4
=1+3/4
=7/4
![](https://rs.olm.vn/images/avt/0.png?1311)
72 x 19 + 8 x 91 x 9 - 12 x 10 x 6
= 9 x 8 x 19 + 8 x 91 x 9 - 12 x 10 x 6
= 72 x 19 + 8 x 9 x 91 - 720
= 72 x 19 + 72 x 91 - 720
= 72 x ( 19 + 91 ) - 720
= 72 x 110 - 720
= 7920 - 720
= 7200.
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\(a.=\frac{4}{13}\times\frac{13}{4}\times\frac{2}{3}\times\frac{3}{2}\)
\(=1\times1\)
\(=1\)
\(b.=\frac{19}{13}+\frac{7}{13}+\frac{14}{6}+\frac{4}{6}+\frac{1}{9}+\frac{17}{9}\)
\(=\frac{26}{13}+\frac{18}{6}+\frac{18}{9}\)
\(=2+3+2\)
\(=7\)
4/13 * 2/3 * 13/4* 3/2= (4/13 * 13/4 )* (2/3 * 3*2) = 1*1=1
19/13 + 14/6 + 1/9 + 4/6 + 7/13 + 17/9 = (19/13 + 7/13) + (14/6 + 4/6) + (1/9 + 17/9) = 2 + 3 + 2 =7
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=9,8 * 43 + 19 * 9,8 - 61 * 9,8
= 9,8 * (43+19-61)
=9,8 * (62-61)
=9,8*1
=9,8
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\dfrac{2}{3}+\dfrac{7}{13}-\dfrac{17}{9}+\dfrac{19}{13}-\dfrac{1}{9}+\dfrac{7}{3}\)
\(=\left(\dfrac{2}{3}+\dfrac{7}{3}\right)+\left(\dfrac{7}{13}+\dfrac{19}{13}\right)-\left(\dfrac{17}{9}+\dfrac{1}{9}\right)\)
\(=\dfrac{9}{3}+\dfrac{26}{13}-\dfrac{18}{9}\)
\(=3+2-2\)
\(=3\)
19.9+9.(37+43)+9
=19.9+9.80+9
=9.(19+80+1)
=9.100
=900
`#Ya`
`= 19 × 9 + 9 × 80 + 9 × 1`
`= 9 × ( 19 + 80 + 1 )`
`= 9 × 100= 900`