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7/15 + 4/15 = 11/15
13/5 - 2 = 13/5 - 10/5 = 3/5
4/7 x 5/8 = 20/56=5/14
8/3 : 8 = 8/3 x 1/8 = 8/24 = 1/3
\(\left(\dfrac{2}{7}+\dfrac{5}{7}\right)+\left(\dfrac{3}{5}+\dfrac{2}{5}\right)+\left(\dfrac{3}{8}+\dfrac{4}{8}+\dfrac{1}{8}\right)+\left(\dfrac{1}{9}+\dfrac{8}{9}\right)=1+1+1+1=4\)
\(\dfrac{5}{8}+\dfrac{6}{8}+\dfrac{5}{8}=\dfrac{5+6+5}{8}=\dfrac{16}{8}=2\)
\(a)\frac{3}{8}+\frac{2}{5}+\frac{5}{8}=\left(\frac{3}{8}+\frac{5}{8}\right)+\frac{2}{5}=1+\frac{2}{5}=\frac{7}{5}\)
\(b)\frac{5}{7}.\frac{2}{3}.\frac{14}{15}=\frac{5.2.14}{7.3.15}=\frac{4}{9}\)
\(c)\frac{3}{8}+\frac{2}{5}.\frac{5}{8}=\frac{3}{8}+\frac{1}{4}=\frac{3}{8}+\frac{2}{8}=\frac{5}{8}\)
\(d)\frac{11}{15}-\left(\frac{2}{3}-\frac{1}{5}\right)=\frac{11}{15}-\frac{7}{15}=\frac{4}{15}\)
~Học tốt~
\(a)\frac{3}{8}+\frac{2}{5}+\frac{5}{8}=\left(\frac{3}{8}+\frac{5}{8}\right)+\frac{2}{5}=1+\frac{2}{5}=\frac{7}{5}\)
\(b)\frac{5}{7}.\frac{2}{3}.\frac{14}{15}=\frac{5.2.14}{7.3.15}=\frac{4}{9}\)
\(c)\frac{3}{8}+\frac{2}{5}.\frac{5}{8}=\frac{3}{8}+\frac{1}{4}=\frac{3}{8}+\frac{2}{8}=\frac{5}{8}\)
\(d)\frac{11}{15}-\left(\frac{2}{3}-\frac{1}{5}\right)=\frac{11}{15}-\frac{7}{15}=\frac{4}{15}\)
~Học tốt~
a) \(\frac{3}{8}+\frac{2}{5}+\frac{5}{8}=\frac{3}{8}+\frac{5}{8}+\frac{2}{5}=\frac{3+5}{8}+\frac{2}{5}\)
\(=1+\frac{2}{5}=\frac{5}{5}+\frac{2}{5}=\frac{7}{5}\)
b) \(\frac{5}{7}\times\frac{2}{3}\times\frac{14}{15}=\frac{5}{7}\times\frac{14}{15}\times\frac{2}{3}=\frac{5\times2\times7}{7\times3\times5}\times\frac{2}{3}\)
\(=\frac{2}{3}\times\frac{2}{3}=\frac{4}{9}\)
c) \(\frac{3}{8}+\frac{2}{5}\times\frac{5}{8}=\frac{3}{8}+\frac{2\times5}{5\times8}=\frac{3}{8}+\frac{2}{8}\)
\(=\frac{5}{8}\)
d) \(\frac{11}{15}-\left(\frac{2}{3}-\frac{1}{5}\right)=\frac{11}{15}-\frac{2}{3}+\frac{1}{5}=\frac{11}{15}-\frac{2\times5}{3\times5}+\frac{3\times1}{3\times5}\)
\(=\frac{11}{15}-\frac{10}{15}+\frac{3}{15}=\frac{11-10+3}{15}=\frac{4}{15}\)
=\(\dfrac{1}{5}\times(\dfrac{2}{8}+\dfrac{5}{8}+\dfrac{1}{8})\)
=\(\dfrac{1}{5}\times\dfrac{8}{8}\)
=\(\dfrac{1}{5}\times1\)
=\(\dfrac{1}{5}\)
a, \(\left(\frac{4}{9}.\frac{3}{7}\right).\frac{7}{4}=\frac{4}{9}\left(\frac{3}{7}.\frac{7}{4}\right)=\frac{4}{9}.\frac{3}{4}=\frac{3}{9}=\frac{1}{3}\)
b, \(\left(\frac{6}{5}.\frac{4}{5}\right).\frac{25}{16}=\frac{6}{5}\left(\frac{4}{5}.\frac{25}{16}\right)=\frac{6}{5}.\frac{5}{4}=\frac{6}{4}=\frac{3}{2}\)
c, \(\left(\frac{7}{8}.\frac{16}{9}\right).\frac{3}{14}=\frac{7}{8}\left(\frac{16}{9}.\frac{3}{14}\right)=\frac{7}{8}.\frac{8}{21}=\frac{7}{21}=\frac{1}{3}\)
89/40
8/5 + 5/8 = 89/40 = 2,225
ai tk mình mình tk lại