Вправа 6.62 гдз 7 клас алгебра Біляніна Білянін Андрух

№ 6.62
Знайти розв'язок системи: $$
\begin{aligned}
& \text { а) }\left\{\begin{array}{l}
2 \cdot(3 x-y)=2 x-10 \\
5-(x-2 y)=4 x+13
\end{array}\right. \\
& \left\{\begin{array}{l}
6 x-2 y=2 x-10 \\
5-x+2 y=4 x+13
\end{array}\right. \\
& \left\{\begin{array}{l}
6 x-2 x-2 y=-10, \\
-x-4 x+2 y=13-5,
\end{array}\right. \\
& \left\{\begin{array}{l}
4 x-2 y=-10 \\
-5 x+2 y=8
\end{array}\right. \\
& 4 x-2 y-5 x+2 y=-10+8 \text {, } \\
& -\mathrm{y}=-2 \text {, } \\
& y=2 \text {, } \\
& 4 x-2 \cdot 2=-10 \text {, } \\
& 4 x-4=-10 \text {, } \\
& 4 x=-6 \text {, } \\
& x=-1,5 \text {. } \\
& (-1,5 ; 2) \text { - розв'язок системи. } \\
& \text { б) }\left\{\begin{array}{l}
-3 \cdot(2 x-y)-3=2 x-5 y \\
7-(x+2 y)=-5 x+18
\end{array}\right. \\
& \left\{\begin{array}{l}
-6 x+3 y-3-2 x+5 y=0 \\
7-x-2 y+5 x=18
\end{array}\right. \\
& \left\{\begin{array}{l}
-8 x+8 y=3 \\
4 x-2 y=11, / \cdot 2
\end{array}\right. \\
& \left\{\begin{array}{l}
-8 x+8 y=3, \\
8 x-4 y=22,
\end{array}\right. \\
& -8 x+8 y+8 x-4 y=3+22 \text {, } \\
& 4 y=25 \text {, } \\
& y=6,25 \text {, } \\
& 4 x-2 \cdot 6,25=11 \text {, } \\
& 4 x=11+12,5,
\end{aligned}
$$
\begin{aligned}
&4 x=23,5\\
&\begin{aligned}
& x=5,875 . \\
& (5,875 ; 6,25) \text { - розв'язати систему. }
\end{aligned}
\end{aligned}