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a: \(=\dfrac{3}{22}\cdot22\cdot\dfrac{3}{11}=3\cdot\dfrac{3}{11}=\dfrac{9}{11}\)
b: \(=\dfrac{5}{6}\cdot\dfrac{2}{5}=\dfrac{1}{3}\)
c: \(=\dfrac{17}{21}\left(\dfrac{3}{5}+\dfrac{2}{5}\right)=\dfrac{17}{21}\)
a: \(=\dfrac{3}{22}\cdot22\cdot\dfrac{3}{11}=3\cdot\dfrac{3}{11}=\dfrac{9}{11}\)
b: \(=\dfrac{5}{6}\cdot\dfrac{2}{5}=\dfrac{1}{3}\)
c: =17/21(3/5+2/5)=17/21
1) 1/5 . 5/4 + 1/5 . 5/4
= (1/5 + 1/5) . 5/4
= 1/5 . 5/4
= 1/4
2)tự làm
1.\(\frac{1}{5}\times\frac{5}{4}+\frac{1}{5}\times\frac{5}{4}\)
\(=\frac{1}{5}\times\frac{5}{4}\times2\)
\(=\frac{1\times5\times2}{5\times4}\)
\(=\frac{1}{2}\)
2.\(\frac{7}{6}\times\frac{2}{5}-\frac{1}{3}\times\frac{2}{5}+\frac{5}{6}\times\frac{2}{5}\)
\(=\frac{2}{5}\times\left(\frac{7}{6}-\frac{1}{3}+\frac{5}{6}\right)\)
\(=\frac{2}{5}\times\left(\frac{7}{6}-\frac{2}{6}+\frac{5}{6}\right)\)
\(=\frac{2}{5}\times\frac{5}{3}\)
\(=\frac{2}{3}\)
a c1 (1/2+1/3)x2/5
=5/6x2/5
=1/3
c2 1/2 x2/5+1/3x2/5
=1/5+2/15
=1/3
a) Cách 1 :
\(\left(\frac{1}{2}+\frac{1}{3}\right)\times\frac{2}{5}\)
= \(\left(\frac{3}{6}+\frac{2}{6}\right)\times\frac{2}{5}\)
= \(\frac{5}{6}\times\frac{2}{5}\)
= \(\frac{10}{30}=\frac{1}{3}\)
Cách 2 :
\(\left(\frac{1}{2}+\frac{1}{3}\right)\times\frac{2}{5}\)
= \(\frac{1}{2}\times\frac{2}{5}+\frac{1}{3}\times\frac{2}{5}\)
= \(\frac{2}{10}+\frac{2}{15}\)
= \(\frac{10}{30}=\frac{1}{3}\)
b) Cách 1 :
\(\frac{3}{5}\times\frac{17}{21}+\frac{17}{21}\times\frac{2}{5}\)
= \(\frac{51}{105}+\frac{34}{105}\)
= \(\frac{85}{105}=\frac{17}{21}\)
Cách 2 :
\(\frac{3}{5}\times\frac{17}{21}+\frac{17}{21}\times\frac{2}{5}\)
= \(\left(\frac{3}{5}+\frac{2}{5}\right)\times\frac{17}{21}\)
= \(1\times\frac{17}{21}\)
= \(\frac{17}{21}\)
Nếu đúng thì mọi người t i c k em nhé:3
a) Cách 1 : (3/4 + 1/2) x 5/7
= 5/4 x 5/7
= 25/28
Cách 2 : (3/4 + 1/2) x 5/7
= 3/4 x 5/7 + 1/2 x 5/7
= 15/28 + 5/14
= 25/28
b) Cách 1 : 5/7 x 13/21 + 2/7 x 13/21
= 65/147 + 26/147
= 13/21
Cách 2 : 5/7 x 13/21 + 2/7 x 13/21
= (5/7 + 2/7) x 13/21
= 1 x 13/21
= 13/21
câu c tự làm
\(a.\left(\dfrac{2}{5}.\dfrac{5}{2}\right).\dfrac{10}{21}=1.\dfrac{10}{21}=\dfrac{10}{21}\)
\(\dfrac{1}{2}.4+\dfrac{3}{4}.4=2+3=5\)
( 1/2 + 1/3 ) x 2/5
c1 = 5/6 x 2/5 = 1/3
c2 = 1/2 x 2/5 + 1/3 x 2/5
= 1/5 + 2/15
= 1/3
3/5 x 17/21 x 2/5
c1 := 17/35 x 2/5 = 34/175
c2 : = (3/5 x 2/5) x 17/21
= 6/25 x 17/21
= 34/175?
( 1/3 - 1/5 ) x 1/2
c1 : = 2/15 x 1/2
= 1/15
c2 : = 1/3 x 1/2 - 1/5 x 1/2
= 1/6 - 1/10
= 1/15