вправа 1039 гдз 7 клас алгебра Мерзляк Полонський
7 клас ➠ алгебра ➠ Мерзляк Полонський
Вправа 1039
Відповідь:
\begin{equation}1)\left\{\begin{matrix}
6x+3=5x-4\left ( 5y+4 \right ),\\3\left ( 2x-3y \right )-6x=8-y;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
6x+3=5x-20y-16,\\ 6x-9y-6x=8-y;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
x+20y=-19,\\ -8y=8;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
x=1,\\ y=-1;
\end{matrix}\right.
\end{equation}
\begin{equation}2)\left\{\begin{matrix}
\frac{x+3}{2}-\frac{y-4}{7}=1,\\6y-x=5;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
\frac{6y-5+3}{2}-\frac{y-4}{7}=1,\\ x=6y-5;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
3y-\frac{y-4}{7}=2,\\x=6y-5;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
\frac{21y}{7}-\frac{y-4}{7}=\frac{14}{7},\\x=6y-5;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
21y-y+4=14,\\ x=6y-5;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
20y=10,\\ x=6y-5;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
y=0,5,\\x=-2;
\end{matrix}\right.
\end{equation}
\begin{equation}3)\left\{\begin{matrix}
\frac{x+y}{8}+\frac{x-y}{6}=4,\\ \frac{3x+y}{4}-\frac{2x-5y}{3}=5;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
3\left ( x+y \right )+4\left ( x-y \right )=96,\\3\left ( 3x+y \right )-4\left ( 2x-5y \right )=60;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
3x+3y+4x-4y=96,\\ 9x+3y-8x+20y=60;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
7x-y=96,\\ x+23y=60;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
y=7x-96,\\ x+23\left ( 7x-96 \right )=60;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
y=7x-96,\\ x+161x-2208=60;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
y=7x-96,\\ 162x=2268;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
y=2,\\ x=14;
\end{matrix}\right.
\end{equation}