\(\frac{17}{21}\times\frac{2}{5}+\frac{17}{21}\times\frac{17}{21}\times\frac{3}{5}\)

\(=\frac{17}{21}\times\left(\frac{2}{5}+\frac{3}{5}\right)\)

\(=\frac{17}{21}\times1\)

\(=\frac{17}{21}\)

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= 17/21 * (3/5 + 2/5)

= 17/21 * 5/5

= 17/21 * 1

= 17/21

Học tốt nha!

=17/21 x 3/5 + 17/ 21 x 2/5

= 17/ 21 x ( 3/5 + 2/5 )
=  17/ 21x     1

= 17/21

Hok tốt !!!

\(-\dfrac{3}{17}+\left(\dfrac{2}{3}+\dfrac{3}{17}\right)=\dfrac{-3}{17}+\dfrac{3}{17}+\dfrac{2}{3}=\dfrac{2}{3}\)

\(\dfrac{-5}{21}+\dfrac{-16}{21}+1=-1+1=0\)

\(\dfrac{-4}{11}\cdot\dfrac{5}{15}\cdot\dfrac{11}{-4}=\dfrac{5}{15}=\dfrac{1}{3}\)

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

CÁCH 1:  

\(\frac{3}{5}\times\frac{17}{21}+\frac{17}{21}\times\frac{2}{5}=\frac{17}{35}+\frac{34}{105}=\frac{17}{21}\)

CÁCH 2:

\(\frac{3}{5}\times\frac{17}{21}+\frac{17}{21}\times\frac{2}{5}=\frac{17}{21}\times(\frac{3}{5}+\frac{2}{5})=\frac{17}{21}\times1=\frac{17}{21}\)

Cách 1:

\(\frac{3}{5}\times\frac{17}{21}+\frac{17}{21}\times\frac{2}{5}\)

\(=\frac{3\times17}{5\times21}+\frac{17\times2}{21\times5}\)

\(=\frac{17}{5\times7}+\frac{34}{105}\)

\(=\frac{17}{35}+\frac{34}{105}\)

\(=\frac{17\times3}{35\times3}+\frac{34}{105}\)

\(=\frac{51+34}{105}\)

\(=\frac{85}{105}\)

\(=\frac{17}{21}\)

Cách 2:

\(\frac{3}{5}\times\frac{17}{21}+\frac{17}{21}\times\frac{2}{5}\)

\(=\frac{17}{21}\times\left(\frac{3}{5}+\frac{2}{5}\right)\)

\(=\frac{17}{21}\times1\)

\(=\frac{17}{21}\)

3/5+2/5+17/21+17/21

=5/5+34/21

=1+34/31

=65/34

C1 : 3/5 + 17/21 + 17/21 x 2/5

=    3/5 + 17/21 x ( 1 + 2/5 ) 

=    3/5 + 17/21 x ( 5/5 + 2/5 ) 

=    3/5  + 17/21 x 7/5 

=    3/5  +    17/15 

=   9/15 + 17/15

= 26/15 

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