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}