新春的3很很踩才吧?

\(7,5x:\left(9-\frac{139}{21}\right)=\frac{63}{25}\)

\(7,5x:\left(\frac{189}{21}-\frac{139}{21}\right)=\frac{63}{25}\)

\(7,5x:\left(\frac{50}{21}\right)=\frac{63}{25}\)

\(7,5x=\frac{63}{25}.\frac{50}{21}\)

\(7,5x=6\)

\(x=6:7,5\)

\(x=\frac{4}{5}\)

vậy \(x=\frac{4}{5}\)

k mk nha vì mk đang âm điểm 

\(7,5x:\left[9-6\frac{13}{21}\right]=2\frac{13}{25}\)

\(\Leftrightarrow7,5x:\left[9-\frac{139}{21}\right]=\frac{63}{25}\)

\(\Leftrightarrow7,5x:\frac{50}{21}=\frac{63}{25}\)

\(\Leftrightarrow7,5x=\frac{63}{25}.\frac{50}{21}\)

\(\Leftrightarrow7,5x=6\)

\(\Leftrightarrow x=6:7,5\)

\(\Leftrightarrow x=\frac{4}{5}=0,8\)

(Chúc bạn học tốt và tíck cho mìk vs nha!)

\(x:(3\frac{1}{2}-5\frac{1}{6})=4\frac{1}{5}-6\frac{2}{3}\)                           b,\((2\frac{1}{3}+3\frac{1}{2})\cdot x=-4\frac{1}{4}+3\frac{1}{7}\)

\(x:\frac{-5}{3}\)=\(\frac{-37}{15}\)                                                              \(\frac{35}{6}\cdot x=\)\(\frac{-31}{28}\)

\(x=\frac{-37}{15}\cdot\frac{-5}{3}\)                                                              \(x=\frac{-31}{28}:\)\(\frac{35}{6}\)

\(x=\frac{37}{9}\)                                                                              \(x=\frac{-93}{490}\)

Vậy x=\(\frac{37}{9}\)                                                                           Vậy x=\(\frac{-93}{490}\)

7,5x:\((9-6\frac{13}{21})=2\frac{13}{25}\)

7,5x:\(\frac{50}{21}\)=\(\frac{63}{25}\)

7,5x=\(\frac{63}{25}:\frac{50}{21}=\frac{1323}{1250}\)

x=\(\frac{1323}{1250}:7,5\)

x=\(\frac{441}{3125}\)

Vậy x=\(\frac{441}{3125}\)

a) \(\frac{2}{\left(x+2\right).\left(x+4\right)}+\frac{4}{\left(x+4\right).\left(x+8\right)}+\frac{6}{\left(x+8\right).\left(x+14\right)}=\frac{x}{\left(x+2\right).\left(x+14\right)}\)

\(\Rightarrow\frac{1}{x+2}-\frac{1}{x+4}+\frac{1}{x+4}-\frac{1}{x+8}+\frac{1}{x+8}-\frac{1}{x+14}=\frac{x}{\left(x+2\right).\left(x+14\right)}\)

\(\Rightarrow\frac{1}{x+2}-\frac{1}{x+14}=\frac{x}{\left(x+2\right).\left(x+14\right)}\)

\(\Rightarrow\frac{x+14}{\left(x+2\right).\left(x+14\right)}-\frac{x+2}{\left(x+2\right).\left(x+14\right)}=\frac{x}{\left(x+2\right).\left(x+14\right)}\)

\(\Rightarrow\frac{x+14-x+2}{\left(x+2\right).\left(x+14\right)}=\frac{x}{\left(x+2\right).\left(x+14\right)}\)

\(\Rightarrow\frac{16}{\left(x+2\right).\left(x+4\right)}=\frac{x}{\left(x+2\right).\left(x+14\right)}\)

\(\Rightarrow x=16\)

Vậy x = 16

\(b,\frac{x+1}{10}+\frac{x+1}{11}+\frac{x+1}{12}=\frac{x+1}{13}+\frac{x+1}{14}\)
\(\Leftrightarrow\frac{x+1}{10}+\frac{x+1}{11}+\frac{x+1}{12}-\frac{x+1}{13}-\frac{x+1}{14}=0\)
\(\Leftrightarrow\left(x+1\right)\left(\frac{1}{10}+\frac{1}{11}+\frac{1}{12}-\frac{1}{13}-\frac{1}{14}\right)=0\)
\(\Leftrightarrow x+1=0\left(vì\frac{1}{10}+\frac{1}{11}+\frac{1}{12}-\frac{1}{13}-\frac{1}{14}\ne0\right)\)
\(\Leftrightarrow x=-1\)
\(\text{Vậy }x=-1\)

b. (x+1)(1/10+1/11+1/12-1/13-1/14)=0

x+1=0 (vì : 1/10+1/11+1/12-1/13-1/14>0)

x=-1