\( \dfrac{7}{8}x - 5x + 45 = \dfrac{{20x + 1,5}}{6}\\ \Leftrightarrow \dfrac{7}{8}x - 5\left( {x - 9} \right) = \dfrac{{20x + 1,5}}{6}\\ \Leftrightarrow 42x - 240x + 2160 = 160x + 12\\ \Leftrightarrow - 358x = - 2148\\ \Leftrightarrow x = 6 \)
\(\frac{7}{8}x-5x+45=\frac{20x+1,5}{6}\)
\(\Leftrightarrow\frac{7x}{8}-\frac{5x+45}{1}=\frac{20x+1,5}{6}\)
\(\Leftrightarrow\frac{7x.3}{8.3}-\frac{24.\left(5x+45\right)}{24}=\frac{4.\left(20x+1,5\right)}{6.4}\)
\(\Leftrightarrow\frac{21x}{24}-\frac{24.\left(5x+45\right)}{24}=\frac{4.\left(20x+1,5\right)}{24}\)
\(\Rightarrow21x-24.\left(5x+45\right)=4.\left(20x+1,5\right)\)
\(\Leftrightarrow21x-120x-1080=80x+6\)
\(\Leftrightarrow-99x-1080=80x+6\)
\(\Leftrightarrow-99x-80x=6+1080\)
\(\Leftrightarrow-179x=1086\)
\(\Leftrightarrow x=1086:\left(-179\right)\)
\(\Leftrightarrow x=-\frac{1086}{179}\)
Vậy phương trình có tập hợp nghiệm là: \(S=\left\{-\frac{1086}{179}\right\}.\)
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\( \dfrac{7}{8}x - 5x + 45 = \dfrac{{20x + 1,5}}{6}\\ \Leftrightarrow \dfrac{7}{8}x - 5\left( {x - 9} \right) = \dfrac{{20x + 1,5}}{6}\\ \Leftrightarrow 21x - 120x + 1080 = 80x + 6\\ \Leftrightarrow - 179x = - 1074\\ \Leftrightarrow x = 6 \)
