1/Thực hiện phép tính
a) \(\left(\frac{2}{5}+\frac{-5}{8}\right):\frac{11}{30}+\frac{1}{8}\)
b) \(\frac{4}{9}+\frac{7}{12}:\frac{3}{8}-\left(\frac{-5}{6}\right)\)
c)\(\left(\frac{2}{5}+\frac{-5}{8}\right):\frac{24}{5}+\left(\frac{13}{8}+\frac{18}{5}\right):\frac{24}{5}\)
d)\(\frac{4}{2\cdot5}+\frac{4}{5\cdot8}+\frac{4}{8\cdot11}...+\frac{4}{20\cdot23}+\frac{4}{23\cdot26}\)
Câu 2: Tìm x
a) \(4\frac{1}{2}+x=5-0,3\)
b)\(\frac{7}{9}-\frac{2}{5}x=\frac{3}{4}x-\frac{1}{6}\)
c)\(\frac{7}{12}-\left(x+70\%\right):1,2=\frac{-5}{4}\)
d)\(|\frac{5}{8}x+\frac{6}{7}|-\frac{4}{7}=\frac{10}{7}\)
Mik cần gấp nhé! Ai nhanh mik tick
Bài 1:
a) b) c) sẽ có bạn giải cho em thôi vì nó dễ tính tay cũng đc
d) \(\frac{4}{2.5}+\frac{4}{5.8}+...+\frac{4}{23.26}\)
\(=\frac{4}{3}.\left(\frac{3}{2.5}+\frac{3}{5.8}+...+\frac{3}{23.26}\right)\)
\(=\frac{4}{3}.\left(\frac{1}{2}-\frac{1}{5}+\frac{1}{5}-\frac{1}{8}+...+\frac{1}{23}-\frac{1}{26}\right)\)
\(=\frac{4}{3}.\left(\frac{1}{2}-\frac{1}{26}\right)\)
\(=\frac{4}{3}.\frac{6}{13}\)
\(=\frac{8}{13}\)
Bài 2:
a) b) c)
d)\(|\frac{5}{8}x+\frac{6}{7}|-\frac{4}{7}=\frac{10}{7}\)
\(\Leftrightarrow|\frac{5}{8}x+\frac{6}{7}|=2\)
\(\Leftrightarrow\orbr{\begin{cases}\frac{5}{8}x+\frac{6}{7}=2\\\frac{5}{8}x+\frac{6}{7}=-2\end{cases}}\)\(\Leftrightarrow\orbr{\begin{cases}\frac{5}{8}x=\frac{8}{7}\\\frac{5}{8}x=\frac{-20}{7}\end{cases}\Leftrightarrow\orbr{\begin{cases}x=\frac{64}{35}\\x=\frac{-32}{7}\end{cases}}}\)
Vậy \(x\in\left\{\frac{64}{35};\frac{-32}{7}\right\}\)
Bài 1 :
a) \(\left(\frac{2}{5}-\frac{5}{8}\right):\frac{11}{30}+\frac{1}{8}\)
\(=\frac{-9}{40}:\frac{11}{30}+\frac{1}{8}\)
\(=\frac{-27}{44}+\frac{1}{8}\)
\(=\frac{-43}{88}\)
Bài 1 :
b) \(\frac{4}{9}+\frac{7}{12}:\frac{3}{8}-\left(\frac{-5}{6}\right)\)
\(=\frac{4}{9}+\frac{14}{9}+\frac{5}{6}\)
\(=\frac{17}{6}\)
Bài 1;
c) \(\left(\frac{2}{5}+\frac{-5}{8}\right):\frac{24}{5}+\left(\frac{13}{8}+\frac{18}{5}\right):\frac{24}{5}\)
\(=\left(\frac{2}{5}+\frac{18}{5}+\frac{-5}{8}+\frac{13}{8}\right):\frac{24}{5}\)
\(=5:\frac{24}{5}\)
\(=\frac{25}{24}\)
Bài 2:
a) \(4\frac{1}{2}+x=5-0,3\)
\(\frac{9}{2}+x=\frac{47}{10}\)
\(x=\frac{1}{5}\)
Vậy \(x=\frac{1}{5}\)
Bài 2:
b)\(\frac{7}{9}-\frac{2}{5}x=\frac{3}{4}x-\frac{1}{6}\)
\(\Leftrightarrow\frac{2}{5}x+\frac{3}{4}x=\frac{1}{6}+\frac{7}{9}\)
\(\Leftrightarrow\frac{23}{20}x=\frac{17}{18}\)
\(\Leftrightarrow x=\frac{170}{207}\)
Bài 2 :
c) \(\frac{7}{12}-\left(x+70\%\right):1,2=\frac{-5}{4}\)
\(\frac{7}{12}-\left(x+\frac{7}{10}\right):\frac{6}{5}=\frac{-5}{4}\)
\(\left(x+\frac{7}{10}\right):\frac{6}{5}=\frac{11}{6}\)
\(x+\frac{7}{10}=\frac{11}{5}\)
\(x=\frac{3}{2}\)
\(\left(\frac{2}{5}+\frac{-5}{8}\right):\frac{11}{30}+\frac{1}{8}\)
\(=\frac{-9}{40}:\frac{11}{30}+\frac{1}{8}\)
\(=\frac{-27}{44}+\frac{1}{8}\)
\(=\frac{-43}{88}\)
~ Hok tốt ~
\(\frac{4}{9}+\frac{7}{12}:\frac{3}{8}-\left(\frac{-5}{6}\right)\)
\(=\frac{4}{9}+\frac{14}{9}-\left(\frac{-5}{6}\right)\)
\(=2-\left(\frac{-5}{6}\right)\)
\(=\frac{17}{6}\)
~ Hok tốt ~
\(\left(\frac{2}{5}+\frac{-5}{8}\right):\frac{24}{5}+\left(\frac{13}{8}+\frac{18}{5}\right):\frac{24}{5}\)
\(=\left(\frac{2}{5}+\frac{-5}{8}+\frac{13}{8}+\frac{18}{5}\right):\frac{24}{5}\)
\(=\left[\left(\frac{2}{5}+\frac{18}{5}\right)+\left(\frac{-5}{8}+\frac{13}{8}\right)\right]:\frac{24}{5}\)
\(=\left(4+1\right):\frac{24}{5}\)
\(=5:\frac{24}{5}\)
\(=\frac{25}{24}\)
~ Hok tốt ~
