Đáp án:
Giải thích các bước giải:
`1`.
`2x-6xy=4`
`=>x.(2-6y)=4`
`=>2x.(1-3y)=4`
`=>x.(1-3y)=2`
`=>x,1-3y inƯ(2)`
`=>x,1-3y in{+-1;+-2}`
$\begin{array}{|c|c|c|}\hline x&1&-1&2&-2 \\\hline1-3y&2&-2&1&-1\\\hline y&\dfrac{-1}{3}&1&0&\dfrac23\\\hline\end{array}$
Vậy $(x,y)\in\left\{\left(1,\dfrac{-1}3\right);\left(-1,1\right);(2,0);\left(-2;\dfrac23\right)\right\}$
`2`.
$\dfrac23+\dfrac13.(2x-1)=-5\\\Rightarrow\dfrac13.(2x-1)=\dfrac{-17}3\\\Rightarrow 2x-1=\dfrac{-17}{9}\\\Rightarrow 2x=\dfrac{-8}{9}\\\Rightarrow x=\dfrac{-4}{9}$
Vậy `x=(-4)/9`.
`3`.
`5*2/3+6,2`
`=10/3+6,2`
`=10/3+31/5`
`=143/15`
