Tìm x
a/ \(\frac{-9}{46}\)- 4\(\frac{1}{23}\): (3\(\frac{1}{4}\)-x: \(\frac{3}{5}\))+2\(\frac{8}{23}\)= 1
b/ 5\(\frac{8}{17}\): (\(\frac{-1}{17}\)): + 3\(\frac{1}{17}\):17\(\frac{1}{3}\)= \(\frac{4}{17}\)
c/ \(\frac{1}{1.4}\)+ \(\frac{1}{4.7}\)+ \(\frac{1}{7.10}\)+ ....+ \(\frac{1}{x\left(x+3\right)}\)= \(\frac{6}{19}\)
a: \(\Leftrightarrow-\dfrac{9}{46}+\dfrac{108}{46}-\dfrac{93}{23}:\left(\dfrac{13}{4}-\dfrac{5}{3}x\right)=1\)
\(\Leftrightarrow\dfrac{93}{23}:\left(\dfrac{13}{4}-\dfrac{5}{3}x\right)=\dfrac{53}{46}\)
\(\Leftrightarrow-\dfrac{5}{3}x+\dfrac{13}{4}=\dfrac{186}{53}\)
=>-5/3x=55/212
hay x=-33/212
c: \(\Leftrightarrow\dfrac{3}{1\cdot4}+\dfrac{3}{4\cdot7}+...+\dfrac{3}{x\left(x+3\right)}=\dfrac{18}{19}\)
\(\Leftrightarrow1-\dfrac{1}{x+3}=\dfrac{18}{19}\)
=>x+3=19
hay x=16
