вправа 1035 гдз 7 клас алгебра Мерзляк Полонський
7 клас ➠ алгебра ➠ Мерзляк Полонський
Вправа 1035
Відповідь:
\begin{equation}1)\left\{\begin{matrix}
4x+y=12,\\7x+2y=20;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
y=12-4x,\\ 7x+2\left ( 12-4x \right )=20;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
y=12-4x,\\7x+24-8x=20;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
y=12-4x,\\-x=-4;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
y=-4,\\x=4;
\end{matrix}\right.
\end{equation}
\begin{equation}2)\left\{\begin{matrix}
x-2y=5,\\3x+8y=1;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
x=5+2y,\\3\left ( 5+2y \right ) +8y=1;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
x=5+2y,\\15+6y+8y=1;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
x=5+2y,\\14y=-14;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
x=3,\\y=-1;
\end{matrix}\right.
\end{equation}
\begin{equation}3)\left\{\begin{matrix}
4y-x=11,\\5x-2y=17;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
x=4y-11,\\5\left ( 4y-11 \right ) -2y=17;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
x=4y-11,\\20y-55-2y=17;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
x=4y-11,\\18y=72;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
x=5,\\y=4;
\end{matrix}\right.
\end{equation}
\begin{equation}4)\left\{\begin{matrix}
6x-y=-1,\\2x-3y=-11;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
y=6x+1,\\2x-3\left ( 6x+1 \right ) =-11;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
y=6x+1,\\2x-18x-3=-11;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
y=6x+1,\\-16x=-8;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
y=4,\\x=0,5;
\end{matrix}\right.
\end{equation}
\begin{equation}5)\left\{\begin{matrix}
x+y=7,\\9y-2x=-25;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
x=7-y,\\9y-2\left ( 7-y \right ) =-25;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
x=7-y,\\9y-14+2y=-25;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
x=7-y,\\11y=-11;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
x=8,\\y=-1;
\end{matrix}\right.
\end{equation}
\begin{equation}6)\left\{\begin{matrix}
5x-3y=0,\\ 15x+2y=55;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
x=0,6y,\\15\cdot 0,6y+2y=55;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
x=0,6y,\\ 9y+2y=55;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
x=0,6y,\\ 11y=55;
\end{matrix}\right.
\end{equation}
\begin{equation}\left\{\begin{matrix}
x=3,\\ y=5.
\end{matrix}\right.
\end{equation}