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đề bài sai sao ý 9/15 mà nếu 9/ 16 thì ko tính thận tiện đc
\(\dfrac{10}{15}\)x\(\dfrac{9}{16}+\dfrac{7}{15}\)x\(\dfrac{10}{15}\)
=> \(\dfrac{10}{15}\)x\(\left(\dfrac{9}{16}+\dfrac{7}{15}\right)\)
=> \(\dfrac{10}{15}\)x\(\dfrac{247}{240}\)
=> \(\dfrac{247}{360}\)
\(\dfrac{9}{10}\times\left(\dfrac{11}{29}+\dfrac{2}{29}+\dfrac{16}{29}\right)=\dfrac{9}{10}\times\dfrac{29}{29}=\dfrac{9}{10}\times1=\dfrac{9}{10}\)
a) \(\dfrac{8}{9}< 1;\dfrac{13}{7}>1\Rightarrow\dfrac{8}{9}< \dfrac{13}{7}\)
b) \(\dfrac{16}{27}>\dfrac{15}{27}>\dfrac{15}{29}\Rightarrow\dfrac{16}{27}>\dfrac{15}{29}\)
a: \(\dfrac{5}{3}\cdot\dfrac{7}{10}=\dfrac{5}{10}\cdot\dfrac{7}{3}=\dfrac{14}{3}>2\)
\(\dfrac{5}{7}:\dfrac{7}{10}=\dfrac{5}{7}\cdot\dfrac{10}{7}=\dfrac{50}{49}< 2\)
=>\(\dfrac{5}{3}\cdot\dfrac{7}{10}>\dfrac{5}{7}:\dfrac{7}{10}\)
b: \(\dfrac{4}{5}\cdot\dfrac{5}{6}=\dfrac{4}{6}=\dfrac{2}{3}\)
\(\dfrac{8}{9}:\dfrac{4}{3}=\dfrac{8}{9}\cdot\dfrac{3}{4}=\dfrac{8}{4}\cdot\dfrac{3}{9}=\dfrac{2}{3}\)
Do đó: \(\dfrac{4}{5}\cdot\dfrac{5}{6}=\dfrac{8}{9}:\dfrac{4}{3}\)
c: \(\dfrac{5}{11}\cdot\dfrac{33}{15}=\dfrac{5}{15}\cdot\dfrac{33}{11}=\dfrac{3}{3}=1\)
\(\dfrac{6}{17}\cdot\dfrac{34}{25}=\dfrac{34}{17}\cdot\dfrac{6}{25}=2\cdot\dfrac{6}{25}=\dfrac{12}{25}< 1\)
=>\(\dfrac{5}{11}\cdot\dfrac{33}{15}>\dfrac{6}{17}\cdot\dfrac{34}{25}\)
d: \(\dfrac{15}{19}\cdot\dfrac{38}{5}=\dfrac{15}{5}\cdot\dfrac{38}{19}=3\cdot2=6\)
\(\dfrac{15}{16}:\dfrac{3}{8}=\dfrac{15}{16}\cdot\dfrac{8}{3}=\dfrac{15}{3}\cdot\dfrac{8}{16}=\dfrac{5}{2}\)<6
=>\(\dfrac{15}{19}\cdot\dfrac{38}{5}>\dfrac{15}{16}:\dfrac{3}{8}\)
\(\dfrac{16}{27}xX=\dfrac{10}{27}-\dfrac{6}{27}\)
\(\dfrac{16}{27}xX=\dfrac{4}{27}\)
\(X=\dfrac{4}{27}:\dfrac{16}{27}\)
X=\(\dfrac{1}{4}\)
16/27x X+2/9=10/27
16/27x X=10/27-2/9
16/27x X=4/27
X=4/27:16/27
X=1/4