Giải:
a) \(\dfrac{3x+2}{5x+7}=\dfrac{3x-1}{5x-3}\)
Áp dụng tính chất của dãy tỉ số bằng nhau, có:
\(\dfrac{3x+2}{5x+7}=\dfrac{3x-1}{5x-3}=\dfrac{3x+2-3x+1}{5x+7-5x+3}=\dfrac{3}{10}\)
\(\Leftrightarrow\dfrac{3x+2}{5x+7}=\dfrac{3}{10}\)
\(\Leftrightarrow30x+20=15x+21\)
\(\Leftrightarrow15x=1\)
\(\Leftrightarrow x=\dfrac{1}{15}\)
Vậy ...
b) \(\dfrac{\left|2x-1\right|}{\dfrac{1}{2}}=\dfrac{18}{5}\)
\(\Leftrightarrow5\left|2x-1\right|=9\)
\(\Leftrightarrow\left|2x-1\right|=\dfrac{9}{5}\)
\(\Leftrightarrow\left[{}\begin{matrix}2x-1=\dfrac{9}{5}\\2x-1=-\dfrac{9}{5}\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{7}{5}\\x=-\dfrac{2}{5}\end{matrix}\right.\)
Vậy ...
