\(3x=2y\Leftrightarrow\frac{x}{2}=\frac{y}{3}\Leftrightarrow\frac{x}{10}=\frac{y}{15}\)

\(7y=5z\Leftrightarrow\frac{y}{5}=\frac{z}{7}\Leftrightarrow\frac{y}{15}=\frac{z}{21}\)

\(\Rightarrow\frac{x}{10}=\frac{y}{15}=\frac{z}{21}=\frac{x-y+z}{10-15+21}=\frac{32}{26}=\frac{16}{13}=\frac{x+y-z}{10+15-21}\)

\(\Rightarrow x+y-z=\frac{16}{13}\cdot4=\frac{64}{13}\)

Theo bài ra ta có: x + z - y = 32

\(\Rightarrow\hept{\begin{cases}3x=2y\Rightarrow21x=14y\\7y=5z\Rightarrow14y=10z\end{cases}\Rightarrow21x=14y=10z}\)\(\Rightarrow\frac{x}{\frac{1}{21}}=\frac{y}{\frac{1}{14}}=\frac{z}{\frac{1}{10}}\)

Áp dụng tính chất của dãy tỉ số bằng nhau ta có:

\(\frac{x}{\frac{1}{21}}=\frac{y}{\frac{1}{14}}=\frac{z}{\frac{1}{10}}=\frac{x+z-y}{\frac{1}{21}+\frac{1}{10}-\frac{1}{14}}=\frac{32}{\frac{8}{105}}=420\)

\(\Rightarrow\hept{\begin{cases}\frac{x}{\frac{1}{21}}=420\Rightarrow x=420\cdot\frac{1}{21}=20\\\frac{y}{\frac{1}{14}}=420\Rightarrow y=420\cdot\frac{1}{14}=30\\\frac{z}{\frac{1}{10}}=420\Rightarrow z=420\cdot\frac{1}{10}=42\end{cases}}\)

=> x + y - z = 20 + 30 - 42 = 8

x + xy + y = 9

x(y + 1) + y = 9

x(y + 1) + y + 1 = 9 + 1

x(y+1) + (y+1) = 10

(x+1)(y+1) = 10

Bạn tự tìm 

Hôm nay OLM trừ điểm CMNR , tick cho mình nhé 

x+xy+y=9

x.(y+1)+y=9

x.(y+1)+y+1=9+1

x.(y+1)+(y+1)=10

(x+1)(y+1)=10

10=1.10;-1.-10;2.5;-2.-5

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