http://olm.vn/hoi-dap/question/117771.html
a)\(\frac{3}{x}-\frac{4}{y}=\frac{1}{5}\)
\(\frac{3x-4y}{xy}=\frac{1}{5}\)
\(15x-20y=xy\)
\(15x-20y-xy=0\)
\(x\left(15-y\right)+300-20y=300\)
\(x\left(15-y\right)+20\left(15-y\right)=300\)
\(\left(15-y\right)\left(x+20\right)=300\)
Ta lập bảng tìm các cặp số nguyên (x;y)...
b) \(\frac{4}{x}+\frac{y}{3}=\frac{5}{6}\)
b) \(\frac{4}{x}+\frac{y}{3}=\frac{5}{6}\)
\(\frac{12+xy}{3y}=\frac{5}{6}\)
\(72+6xy=15x\)
\(3x\left(5-3\right)y=72\)
\(x\left(5-3y\right)=24\)
Tương tự...