Вправа 1110 алгебра Бевз гдз 7 клас

№ 1110 $$
\begin{aligned}
& \text { a) }\left\{\begin{array}{c}
2 x+y=17 \\
2 x-y=3
\end{array}+\right. \\
& 4 x=20 \\
& x=5 \\
& 2 \cdot 5-y=3 \\
& y=10-3 \\
& y=7
\end{aligned}
$$
$$
\begin{aligned}
& \text { б) }\left\{\begin{array}{l}
3 u-v=26 \\
5 u+v=38 ;
\end{array}+\right. \\
& 8 u=64 \\
& u=8 \\
& 5 \cdot 8+v=38 \\
& v=38-40 \\
& v=-2
\end{aligned}
$$ $$
\begin{aligned}
& \text { в) }\left\{\begin{array}{l}
x-2 y=5, \\
3 x+2 y=7 ;
\end{array}+\right. \\
& 4 x=12 \\
& x=3 \\
& 3 \cdot 3+2 y=7 \\
& 2 y=7-9 \\
& y=-2: 2
\end{aligned}
$$ $$
\begin{aligned}
& \text { г) }\left\{\begin{array}{c}
3 x+4 y=25 \\
7 x-4 y=5
\end{array}+\right. \\
& 10 x=30 \\
& x=3 \\
& 3 \cdot 3+4=25 \\
& 4 y=25-9 \\
& y=16: 4 \\
& y=4 .
\end{aligned}
$$