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Ta có :
\(x+y=\frac{1}{2}\)
\(y+z=\frac{1}{3}\)
\(z+x=\frac{1}{4}\)
\(\Rightarrow\)\(x+y+y+z+z+x=\frac{1}{2}+\frac{1}{3}+\frac{1}{4}\)
\(\Rightarrow\)\(2x+2y+2z=\frac{13}{12}\)
\(\Rightarrow\)\(2\left(x+y+z\right)=\frac{13}{12}\)
\(\Rightarrow\)\(x+y+z=\frac{13}{12}:2\)
\(\Rightarrow\)\(x+y+z=\frac{13}{24}\)
Do đó :
\(x+y+z=\frac{13}{24}\)
\(\Rightarrow\)\(x=\frac{13}{24}-\left(y+z\right)=\frac{13}{24}-\frac{1}{3}=\frac{5}{24}\)
\(\Rightarrow\)\(y=\frac{13}{24}-\left(z+x\right)=\frac{13}{24}-\frac{1}{4}=\frac{7}{24}\)
\(\Rightarrow\)\(z=\frac{13}{24}-\left(x+y\right)=\frac{13}{24}-\frac{1}{2}=\frac{1}{24}\)
Vậy \(x=\frac{5}{24};y=\frac{7}{24};z=\frac{1}{24}\)
Chúc bạn học tốt ~
x + y = 7/12 => x = 7/12 - y
y + z = -19/24 => z = -19/24 - y
Mà z + x = 1/8 => 7/12 - y - 19/24 - y = 1/8
=> 2y = 7/12 - 19/24 - 1/8 => 2y = -1/3
=> y = -1/6
số cặp x,y là :
N :2 = ??
đ/s:.......
số cặp x,y,z là :
N* :3=?
\(\hept{\begin{cases}x+y+z+t=1\\x+y+z=2\end{cases}}\)
\(\Rightarrow\left(x+y+z+t\right)-\left(x+y+z\right)=1-2\)
\(\Rightarrow t=-1\)
\(\hept{\begin{cases}x+y+z+t=1\\y+z+t=3\end{cases}}\)
\(\Rightarrow\left(x+y+z+t\right)-\left(y+z+t\right)=1-3\)
\(\Rightarrow x=-2\)
\(\hept{\begin{cases}x+y+z+t=1\\z+x+t=4\end{cases}}\)
\(\Rightarrow\left(x+y+z+t\right)-\left(z+x+t\right)=1-4\)
\(\Rightarrow y=-3\)
\(x+y+z+t=1\)
\(\Rightarrow\left(-2\right)+\left(-3\right)+\left(-1\right)+t=1\)
\(\Rightarrow\left(-6\right)+t=1\)
\(\Rightarrow t=7\)
Ta có:
\(x+y+y+z+z+x=\frac{1}{2}+\frac{1}{3}+\frac{1}{4}\)
\(\Rightarrow2\left(x+y+z\right)=\frac{13}{12}\Leftrightarrow x+y+z=\frac{13}{12}.\frac{1}{2}=\frac{13}{24}\)
\(\cdot x+y=\frac{1}{2}\Leftrightarrow z=\frac{13}{24}-\frac{1}{2}=\frac{1}{24}\)
\(\cdot y+z=\frac{1}{3}\Leftrightarrow x=\frac{13}{24}-\frac{1}{3}=\frac{5}{24}\)
\(\cdot y=\frac{13}{24}-\frac{1}{24}-\frac{5}{24}=\frac{7}{24}\)
Vậy \(x=\frac{5}{24};y=\frac{7}{24};z=\frac{1}{24}\)
Ta có: y + z = \(\frac{1}{3}\); z + x = \(\frac{1}{4}\).
=> y lớn hơn x : \(\frac{1}{3}-\frac{1}{4}=\frac{1}{12}\).
x + y = \(\frac{1}{2}\)và y - x = \(\frac{1}{12}\)=> x = \(\left(\frac{1}{2}-\frac{1}{12}\right):2=\frac{5}{24}\)
=> y = \(\frac{1}{2}-\frac{5}{24}=\frac{7}{24}\)
=> z = \(\frac{1}{4}-\frac{5}{24}=\frac{1}{24}\)
\(\hept{\begin{cases}x+y=3\\y+z=-1\\z+x=-2\end{cases}}\)
\(\Rightarrow\left(x+y\right)+\left(y+z\right)+\left(z+x\right)=0\)
\(\Rightarrow2\left(x+y+z\right)=0\)
\(\Rightarrow x+y+z=0\)
\(\hept{\begin{cases}z=0-\left(x+y\right)=-3\\x=0-\left(y+z\right)=1\\y=0-\left(z+x\right)=2\end{cases}}\)
Ko bít