Các bác ,các ah ,các chj ai jup đc jup e vs ak
câu a you tự làm nhé
b) \(xy+x-y=0\)
\(\Rightarrow xy+x-y-1=-1\)
\(\Rightarrow x\left(y+1\right)-1\left(y+1\right)=-1\)
\(\Rightarrow\left(x-1\right)\left(y+1\right)=-1\)
Tự xét ước
c) \(xy+2x+y+1=0\)
\(\Rightarrow xy+2x+y+2=1\)
\(\Rightarrow x\left(y+2\right)+1\left(y+2\right)=1\)
\(\Rightarrow\left(x+1\right)\left(y+2\right)=1\)
Xét ước
\(\dfrac{1}{x}+\dfrac{1}{y}=\dfrac{1}{2}\)
\(\Leftrightarrow\dfrac{y}{xy}+\dfrac{x}{xy}=\dfrac{1}{2}\)
\(\Leftrightarrow\dfrac{x+y}{xy}=\dfrac{1}{2}\)
\(\Leftrightarrow2x+2y=xy\)
\(\Leftrightarrow2x+2y-xy=0\)
\(\Leftrightarrow2x+2y-xy-4=-4\)
\(\Leftrightarrow x\left(2-y\right)-2\left(2-y\right)=-4\)
\(\Leftrightarrow\left(x-2\right)\left(2-y\right)=-4\)
Tiếp tục xét ước
