a, \(x=\dfrac{17.15}{51}=5\)
b, \(x=\dfrac{1}{9}+\dfrac{5}{6}=\dfrac{6+45}{54}=\dfrac{51}{54}=\dfrac{17}{18}\)
c, \(x+\dfrac{2}{7}=\dfrac{1}{9}+\dfrac{5}{9}=\dfrac{2}{3}\Leftrightarrow x=\dfrac{2}{3}-\dfrac{2}{7}=\dfrac{14-6}{21}=\dfrac{8}{21}\)
d, đk x khác 0
\(\dfrac{3}{5}+\dfrac{1}{2x}=-\dfrac{5}{4}\Leftrightarrow\dfrac{1}{2x}=-\dfrac{5}{4}-\dfrac{3}{5}=\dfrac{-25-12}{20}=-\dfrac{37}{20}\)
\(\Rightarrow-37.2x=20\Leftrightarrow x=\dfrac{20}{-37}:2=-\dfrac{20}{37}.\dfrac{1}{2}=-\dfrac{10}{37}\)(tm)
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