1) \(=\left(\frac{3}{5}+\frac{2}{5}\right).\frac{6}{11}\)

\(=1.\frac{6}{11}\)

\(=\frac{6}{11}\)

2)\(\frac{17}{25}.\left(\frac{11}{19}+\frac{6}{19}+\frac{2}{19}\right)\)

\(=\frac{17}{25}.1\)

\(=\frac{17}{25}\)

2.\(\frac{17}{25}.\frac{11}{19}+\frac{17}{25}.\frac{6}{19}+\frac{17}{25}.\frac{2}{19}=\frac{17}{25}\left(\frac{11}{19}+\frac{6}{19}+\frac{2}{19}\right)\\ =\frac{17}{25}.1\\ =\frac{17}{25}\)

\(\dfrac{3}{5}+\dfrac{6}{11}+\dfrac{7}{13}+\dfrac{2}{5}+\dfrac{16}{11}+\dfrac{19}{13}\\ =\left(\dfrac{3}{5}+\dfrac{2}{5}\right)+\left(\dfrac{6}{11}+\dfrac{16}{11}\right)+\left(\dfrac{7}{13}+\dfrac{19}{13}\right)\\ =\dfrac{5}{5}+\dfrac{22}{11}+\dfrac{26}{13}\\ =1+2+2\\ =5\)

5

a) \(\dfrac{7}{9}\times\dfrac{13}{25}\times\dfrac{9}{7}=\left(\dfrac{7}{9}\times\dfrac{9}{7}\right)\times\dfrac{13}{25}=1\times\dfrac{13}{25}=\dfrac{13}{25}\)

b) \(\dfrac{5}{9}\times\dfrac{21}{25}+\dfrac{21}{25}\times\dfrac{4}{9}\)

\(=\dfrac{21}{25}\times\left(\dfrac{5}{9}+\dfrac{4}{9}\right)\)

\(=\dfrac{21}{25}\times1=\dfrac{21}{25}\)

c) \(\dfrac{19}{5}\times\dfrac{11}{16}-\dfrac{9}{5}\times\dfrac{11}{16}\)

\(=\dfrac{11}{16}\times\left(\dfrac{19}{5}-\dfrac{9}{5}\right)\)

\(=\dfrac{11}{16}\times2=\dfrac{22}{16}=\dfrac{11}{8}\)

a) 5

b) 11/6

11 + 5 + 19 + 6 + 4

= (11 + 19) + (6 + 4) + 5

=     30      +     10   + 5

=              45

số đó là

45

bn ủng ho

mình nhé bn

\(\frac{3}{5}+\frac{6}{11}+\frac{7}{13}+\frac{2}{5}+\frac{16}{11}+\frac{19}{13}=\left(\frac{3}{5}+\frac{2}{5}\right)\left(\frac{6}{11}+\frac{16}{11}\right)\left(\frac{7}{13}+\frac{19}{13}\right)=1+2+2=5\)

Ta có:3/5+2/5=5/5=1; 6/11+16/11=22/11=2; 7/13+19/13=26/13=2

kết quả là 1+2+2=5

\(\frac{3}{5}+\frac{6}{11}+\frac{7}{13}+\frac{2}{5}+\frac{16}{11}+\frac{19}{13}\)

\(=\left(\frac{3}{5}+\frac{2}{5}\right)+\left(\frac{6}{11}+\frac{16}{11}\right)+\left(\frac{7}{13}+\frac{19}{13}\right)\)

\(=\frac{5}{5}+\frac{22}{11}+\frac{26}{13}\)

\(=1+2+2=5\)

a )     \(\frac{5}{11}\times\frac{7}{25}\times\frac{15}{11}\times\frac{1}{5}\)

\(=\frac{5\times7\times15\times1}{11\times25\times11\times5}\)

\(=\frac{1\times7\times3\times1}{11\times5\times11\times1}\)

\(=\frac{21}{\left(10\times5+5\times1\right)\times11}\)

\(=\frac{21}{55\times11}\)

\(=\frac{21}{55\times10+55}\)

\(=\frac{21}{550+55}\)

\(=\frac{21}{605}\)   ( quá đơn giản ) 

\(\)

A) \(\frac{5}{11}\times\frac{7}{25}-\frac{15}{11}\times\frac{1}{5}\)

\(=\frac{5\times7}{11\times25}-\frac{15\times1}{11\times5}\)

\(=\frac{35}{10\times25+25}-\frac{15}{55}\)

\(=\frac{35}{250+25}-\frac{15}{55}\)

\(=\frac{35}{275}-\frac{15}{55}\)

\(=\frac{7}{55}-\frac{15}{55}\)

\(=\frac{7-15}{55}\)

\(=\frac{-8}{55}\)

bài ở dưới mới đúng nhà ( bài không có chữ đơn giản quá ) 

\(\dfrac{3}{11}\text{×}\dfrac{7}{19}+\dfrac{3}{11}\text{×}\dfrac{10}{19}+\dfrac{3}{11}\text{×}\dfrac{1}{19}=\dfrac{3}{11}\text{×}\left(\dfrac{7}{19}+\dfrac{10}{19}+\dfrac{2}{19}\right)=\dfrac{3}{11}\text{×}1=\dfrac{3}{11}\)