Question

Tìm x,y thuộc z. Sao cho xy=3(y-x)

Answer 1

\(xy=3y-3x\Leftrightarrow\left(xy+3y\right)-\left(3y+9\right)=-9\)

\(x\left(y+3\right)-3\left(y+3\right)=\left(y+3\right)\left(x-3\right)=-9\)

\(\left\{{}\begin{matrix}y+3=\left\{-9,-3,-1,1,3,9\right\}\\x-3=\left\{1,3,9,-9,-3,-1\right\}\end{matrix}\right.\)\(\Rightarrow\left\{{}\begin{matrix}y=\left\{-12,-6,-4,-2,0,-6\right\}\\x=\left\{4,7,12,-6,0,-2\right\}\end{matrix}\right.\)

Answer 2

(-3x²y-4xy+5)+(2xy+3x²y-4)