Bài `3:`
`d, (2x-3)(3/4x+1)=0`
`=>` $\left[\begin{matrix} 2x-3=0\\\frac{3}{4}+1=0\end{matrix}\right.$
`=>` $\left[\begin{matrix} 2x=0+3\\\frac{3}{4}x=0-1\end{matrix}\right.$
`=>` $\left[\begin{matrix} 2x=3\\\frac{3}{4}x=-1\end{matrix}\right.$
`=>` $\left[\begin{matrix} x=3:2\\x=(-1):\frac{3}{4}\end{matrix}\right.$
`=>` $\left[\begin{matrix} x=\frac{3}{2}\\x=\frac{-4}{3}\end{matrix}\right.$
Vậy `x in {3/2; (-4/3)}`
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`e, 1/2x+3/5x=-33/25`
`=> x.(1/2+3/5)=-33/25`
`=> x.11/10=-33/25`
`=> x=(-33/25):11/10`
`=> x=-6/5`
