\(\frac{2}{3}+\frac{4}{5}+\frac{5}{6}=\frac{2\times10}{3\times10}+\frac{4\times6}{5\times6}+\)\(\frac{5\times5}{6\times5}\)

\(=\frac{20}{30}+\frac{24}{30}+\frac{25}{30}\)

\(=\frac{20+24+25}{30}=\frac{44+25}{30}=\frac{69}{30}=\frac{23}{10}\)

23/10

81 x 4 = 324

81 x4 =324

16 x 3,14 = 50,24

=50,24 

tk for me

a)\(\frac{4}{9}\)

b)\(\frac{1}{3}\)

c)\(\frac{3}{4}\)

d)\(\frac{2}{11}\)

e)\(\frac{5}{12}\)

g)\(\frac{3}{5}\)

#H

\(a,\frac{5}{9}+\frac{4}{9}=1\)

\(b,\frac{2}{3}+\frac{1}{3}=1\)

\(c,\frac{1}{4}+\frac{3}{4}=1\)

\(d,\frac{9}{11}+\frac{2}{11}=1\)

\(e,\frac{7}{12}+\frac{5}{12}=1\)

\(g,\frac{2}{5}+\frac{3}{5}=1\)

4/12=2/6

5/10=1/2=3/6

chúc bạn học tốt 

1,       4/12

=2/6

 2,      5/10

=1/2

=3/6

\(\frac{4}{12},\frac{8}{24}\)

Ta có : $\frac{4}{12}=\frac{1}{3}=\frac{2}{6}$

          $=\frac{3}{9}=\frac{5}{15}=\frac{6}{18}$

        $=\frac{7}{21}=\frac{8}{24}=\frac{9}{27}$

b) \(\left(\frac{7}{27}+\frac{8}{27}\right)+\frac{12}{27}\)

\(=\frac{7}{27}+\frac{8}{27}+\frac{12}{27}\)

\(=\frac{27}{27}=1\)

\(27+\left(\frac{8}{27}+\frac{12}{27}\right)\)

\(=27+\frac{20}{27}\)

\(=\frac{729}{27}\)

c) \(\left(\frac{4}{9}+\frac{8}{9}\right)+\frac{3}{9}\)

\(=\frac{4}{9}+\frac{8}{9}+\frac{3}{9}\)

\(=\frac{15}{9}=\frac{5}{3}\)

\(\frac{4}{9}+\left(\frac{8}{9}+\frac{3}{9}\right)\)

\(=\frac{15}{9}=\frac{5}{3}\)

#H

na ní vãi

1/ 6:1/3

hay

1/6:1/3 

hả bạn

1/6:1/3=1/6 x 3 =1/2

2/10464-20 \(\approx-20\)

9999999999999999999999999999999x4444444444444444446666666666666666666644444444444444=888888000099977766655544443332211

1/2+6/7= 7/14+12/14=19/14

8/27+24/32=113/108