a) \(\dfrac{2x+7}{3}+\dfrac{x-2}{4}=-2\)
\(\Leftrightarrow\dfrac{4\left(2x+7\right)}{12}+\dfrac{3\left(x-2\right)}{12}=\dfrac{-24}{12}\)
\(\Leftrightarrow8x+28+3x-6=-24\)
\(\Leftrightarrow11x=-46\)
\(\Leftrightarrow x=\dfrac{-46}{11}\)
Vậy S={-46/11}
b) \(\dfrac{x-1}{4}+\dfrac{2x+1}{3}=x\)
\(\Leftrightarrow\dfrac{3\left(x-1\right)}{12}+\dfrac{4\left(2x+1\right)}{12}=\dfrac{12x}{12}\)
\(\Leftrightarrow3x-3+8x+4=12x\)
\(\Leftrightarrow-x=-1\)
\(\Leftrightarrow x=1\)
Vậy S={1}
c) \(\dfrac{2x-1}{2}+\dfrac{4x+3}{5}=3x\)
\(\Leftrightarrow\dfrac{5\left(2x-1\right)}{10}+\dfrac{2\left(4x+3\right)}{10}=\dfrac{30x}{10}\)
\(\Leftrightarrow10x-5+8x+6=30x\)
\(\Leftrightarrow-12x=-1\)
\(\Leftrightarrow x=\dfrac{1}{12}\)
Vậy S={1/12}
d). \(\dfrac{x+1}{4}+\dfrac{3x-2}{12}=\dfrac{2x+3}{15}\)
\(\Leftrightarrow\dfrac{15\left(x+1\right)}{60}+\dfrac{5\left(3x-2\right)}{60}=\dfrac{4\left(2x+3\right)}{60}\)
\(\Leftrightarrow15x+15+15x-10=8x+12\)
\(\Leftrightarrow22x=7\)
\(\Leftrightarrow x=\dfrac{7}{22}\)
Vậy S={7/22}