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\(A\cdot\left(1-\dfrac{1}{4}\right)\cdot\left(1-\dfrac{1}{9}\right)\cdot\left(1-\dfrac{1}{16}\right)\left(1-\dfrac{1}{25}\right)=1\dfrac{3}{5}\)
=>\(A\cdot\left(1-\dfrac{1}{2}\right)\left(1-\dfrac{1}{3}\right)\left(1-\dfrac{1}{4}\right)\left(1-\dfrac{1}{5}\right)\left(1+\dfrac{1}{2}\right)\left(1+\dfrac{1}{3}\right)\left(1+\dfrac{1}{4}\right)\left(1+\dfrac{1}{5}\right)=\dfrac{8}{5}\)
=>\(A\cdot\dfrac{1}{2}\cdot\dfrac{2}{3}\cdot\dfrac{3}{4}\cdot\dfrac{4}{5}\cdot\dfrac{3}{2}\cdot\dfrac{4}{3}\cdot\dfrac{5}{4}\cdot\dfrac{6}{5}=\dfrac{8}{5}\)
=>\(A\cdot\dfrac{1}{5}\cdot\dfrac{6}{2}=\dfrac{8}{5}\)
=>\(A\cdot3=8\)
=>A=8/3
\(\dfrac{15}{16}:\dfrac{5}{8}\times\dfrac{3}{4}\)
\(=\dfrac{15}{16}\times\dfrac{8}{5}\times\dfrac{3}{4}\)
\(=\dfrac{3}{2}\times\dfrac{3}{4}\)
\(=\dfrac{9}{8}\)
_________________
\(\dfrac{21}{4}\times\dfrac{16}{14}\times\dfrac{1}{2}\times\dfrac{8}{3}\)
\(=6\times\dfrac{4}{3}\)
\(=8\)
\(A=29\dfrac{1}{2}\cdot\dfrac{2}{3}+39\dfrac{1}{3}\cdot\dfrac{3}{4}+\dfrac{5}{6}\)
\(=\dfrac{59}{2}\cdot\dfrac{2}{3}+\dfrac{118}{3}\cdot\dfrac{3}{4}+\dfrac{5}{6}\)
\(=\dfrac{59}{3}+\dfrac{118}{4}+\dfrac{5}{6}\)
\(=\dfrac{59}{3}+\dfrac{59}{2}+\dfrac{5}{6}\)
\(=59\cdot\left(\dfrac{1}{3}+\dfrac{1}{2}\right)+\left(\dfrac{1}{3}+\dfrac{1}{2}\right)\)
\(=\dfrac{5}{6}\cdot\left(59+1\right)=\dfrac{5}{6}\cdot60=50\)
\(3\dfrac{7}{8}\times x-2\dfrac{3}{4}=3\dfrac{6}{12}\times\dfrac{10}{8}-\dfrac{1}{3}\)
\(\dfrac{31}{8}\times x-\dfrac{11}{4}=\dfrac{7}{2}\times\dfrac{10}{8}-\dfrac{1}{3}\)
\(\dfrac{31}{8}\times x-\dfrac{11}{4}=\dfrac{35}{8}-\dfrac{1}{3}\)
\(\dfrac{31}{8}\times x=\dfrac{97}{24}+\dfrac{11}{4}\)
\(\dfrac{31}{8}\times x=6\dfrac{19}{24}\)
\(x=1\dfrac{70}{93}\)
42/12x10/8-1/3= 84/24x30/24-8/24= 315/72-8/24= 291/72
xong bạn rút gọn nha
\(3\dfrac{1}{5}\times\dfrac{10}{11}+1\dfrac{2}{11}\\ =\dfrac{16}{5}\times\dfrac{10}{11}+\dfrac{13}{11}\\ =\dfrac{16\times10}{5\times11}+\dfrac{13}{11}\\ =\dfrac{160}{55}+\dfrac{13}{11}\\ =\dfrac{32}{11}+\dfrac{13}{11}\\ =\dfrac{32+13}{11}\\ =\dfrac{45}{11}\)
\(5\dfrac{1}{3}:1\dfrac{2}{3}-1\dfrac{1}{5}\\ =\dfrac{16}{3}:\dfrac{5}{3}-\dfrac{6}{5}\\ =\dfrac{16}{3}\times\dfrac{3}{5}-\dfrac{6}{5}\\ =\dfrac{16\times3}{3\times5}-\dfrac{6}{5}\\ =\dfrac{48}{15}-\dfrac{6}{5}\\ =\dfrac{16}{5}-\dfrac{6}{5}\\ =\dfrac{16-6}{5}\\ =\dfrac{10}{5}\\ =2\)
\(3\dfrac{1}{5}\times\dfrac{10}{11}+1\dfrac{2}{11}\\ =\dfrac{3\times5+1}{5}\times\dfrac{10}{11}+\dfrac{1\times11+2}{11}\\ =\dfrac{16}{5}\times\dfrac{10}{11}+\dfrac{13}{11}\\ =\dfrac{160}{55}+\dfrac{13}{11}\\ =\dfrac{32}{11}+\dfrac{13}{11}\\ =\dfrac{45}{11}\)
\(5\dfrac{1}{3}:1\dfrac{2}{3}-1\dfrac{1}{5}\\ =\dfrac{5\times3+1}{3}:\dfrac{1\times3+2}{3}-\dfrac{1\times5+1}{5}\\ =\dfrac{16}{3}:\dfrac{5}{3}-\dfrac{6}{5}\\ =\dfrac{16}{3}\times\dfrac{3}{5}-\dfrac{6}{5}\\ =\dfrac{16}{5}-\dfrac{6}{5}\\ =\dfrac{10}{5}=2\)
\(2\times\left(x-\dfrac{1}{2}\right)=3\dfrac{1}{3}\\ \Leftrightarrow2\times\left(x-\dfrac{1}{2}\right)=\dfrac{3\times3+1}{3}\\ \Leftrightarrow2\times\left(x-\dfrac{1}{2}\right)=\dfrac{10}{3}\\ \Leftrightarrow x-\dfrac{1}{2}=\dfrac{10}{3}:2\\ \Leftrightarrow x-\dfrac{1}{2}=\dfrac{5}{3}\\ \Leftrightarrow x=\dfrac{5}{3}+\dfrac{1}{2}=\dfrac{5\times2+1\times3}{6}\\ \Leftrightarrow x=\dfrac{13}{6}\)
\(\dfrac{12}{5}\times\dfrac{5}{9}-\dfrac{1}{3}\\ =\dfrac{4}{3}-\dfrac{1}{3}=1\)
\(\dfrac{12}{5}\cdot\dfrac{5}{9}-\dfrac{1}{3}=\dfrac{4}{3}-\dfrac{1}{3}=1\)
\(A=1\dfrac{1}{2}\times1\dfrac{1}{3}\times1\dfrac{1}{4}\times....\times1\dfrac{1}{2020}\times1\dfrac{1}{2021}\\ =\dfrac{3}{2}\times\dfrac{4}{3}\times\dfrac{5}{4}\times\dfrac{6}{5}\times....\times\dfrac{2022}{2021}\\ =\dfrac{3\times4\times5\times6\times.....\times2022}{2\times3\times4\times5\times....\times2021}\\ =\dfrac{2022}{2}=1011\)