Question

[Emily Nain]

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

Answer 1

[Lê Tài Bảo Châu]

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 \(x\in\left\{\frac{64}{35};\frac{-32}{7}\right\}\)

Answer 2

[Lê Tài Bảo Châu]

Bài 1 :

a) \(\left(\frac{2}{5}-\frac{5}{8}\right):\frac{11}{30}+\frac{1}{8}\)

\(=\frac{-9}{40}:\frac{11}{30}+\frac{1}{8}\)

\(=\frac{-27}{44}+\frac{1}{8}\)

\(=\frac{-43}{88}\)