Toán Lớp 7: $\frac{x-1}{2}$ =$\frac{y+3}{4}$= $\frac{z-5}{6}$ và 5z-3x-4y=50
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Toán Lớp 7: $\frac{x-1}{2}$ =$\frac{y+3}{4}$= $\frac{z-5}{6}$ và 5z-3x-4y=50
làm giúp mình với ạ
Comments ( 1 )
\dfrac{{x – 1}}{2} = \dfrac{{y + 3}}{4} = \dfrac{{z – 5}}{6}\\
= \dfrac{{3\left( {x – 1} \right)}}{6} = \dfrac{{4\left( {y + 3} \right)}}{{16}} = \dfrac{{5\left( {z – 5} \right)}}{{30}}\\
= \dfrac{{3x – 3 + 4y + 12 – 5z + 25}}{{6 + 16 – 30}}\\
= \dfrac{{\left( {3x + 4y – 5z} \right) – 3 + 12 + 25}}{{ – 8}}\\
= \dfrac{{ – 50 + 34}}{{ – 8}}\\
= \dfrac{{ – 16}}{{ – 8}}\\
= 2\\
\Leftrightarrow \left\{ \begin{array}{l}
x – 1 = 4\\
y + 3 = 8\\
z – 5 = 12
\end{array} \right.\\
\Leftrightarrow \left\{ \begin{array}{l}
x = 5\\
y = 5\\
z = 17
\end{array} \right.\\
Vậy\,x = y = 5;z = 17
\end{array}$