Вправа 6.44 гдз 7 клас алгебра Біляніна Білянін Андрух

№ 6.44
Розв'язати систему рівнянь: $$
\begin{aligned}
& \text { a) }\left\{\begin{array}{l}
3 x+4 y=-13, \\
2 x-5 y=22 ;
\end{array}\right. \\
& \left\{\begin{array}{l}
3 x+4 y=-13, \\
2 x=22+5 y,
\end{array}\right. \\
& \left\{\begin{array}{l}
3 \cdot(11+2,5 y)+4 y=-13, \\
x=11+2,5 y,
\end{array}\right. \\
& \left\{\begin{array}{l}
33+7.5 y+4 y=-13, \\
x=11+2,5 y,
\end{array}\right. \\
& \left\{\begin{array}{l}
11,5 y=-46, \\
x=11+2,5 y,
\end{array}\right. \\
& \left\{\begin{array}{l}
y=-4, \\
x=11+2,5 \cdot(-4),
\end{array}\right. \\
& \left\{\begin{array}{l}
y=-4, \\
x=1
\end{array}\right. \\
& \text { б) }\left\{\begin{array}{l}
3 x+2 y=0, \\
7 x+4 y=-2 ;
\end{array}\right. \\
& \left\{\begin{array}{l}
2 y=-3 x, \\
7 x+2 \cdot(-3 x)=-2,
\end{array}\right. \\
& \left\{\begin{array}{l}
2 y=-3 x, \\
7 x-6 x=-2,
\end{array}\right. \\
& \left\{\begin{array}{l}
2 y=-3 \cdot(-2), \\
x=-2,
\end{array}\right. \\
& \left\{\begin{array}{l}
2 y=6, \\
x=-2,
\end{array}\right. \\
& \left\{\begin{array}{l}
y=3, \\
x=-2 .
\end{array}\right. \\
& \text { в }\left\{\begin{array}{l}
\text { y }=2 y=6, \\
9 x+3 y=33 ;
\end{array}\right. \\
& \left\{\begin{array}{l}
2 y=8 x-6, \\
9 x+3 y=33,
\end{array}\right.
\end{aligned}
$$
\begin{aligned}
&\begin{aligned}
& \left\{\begin{array}{l}
y=4 x-3, \\
9 x+3 \cdot(4 x-3)=33
\end{array}\right. \\
& \left\{\begin{array}{l}
y=4 x-3, \\
9 x+12 x-9=33,
\end{array}\right. \\
& \left\{\begin{array}{l}
y=4 x-3, \\
21 x=42,
\end{array}\right. \\
& \left\{\begin{array}{l}
y=4 x-3, \\
x=2,
\end{array}\right. \\
& \left\{\begin{array}{l}
y=4 \cdot 2-3, \\
x=2,
\end{array}\right.
\end{aligned}\\
&\begin{aligned}
& \left\{\begin{array}{l}
y=5 \\
x=2
\end{array}\right. \\
& \text { г) }\left\{\begin{array}{l}
4 x-6 y=24 \\
10 x-2 y=34
\end{array}\right. \\
& \left\{\begin{array}{l}
4 x-6 y=24, \\
2 y=10 x-34
\end{array}\right. \\
& \left\{\begin{array}{l}
4 x-6 \cdot(5 x-17)=24 \\
y=5 x-17,
\end{array}\right. \\
& \left\{\begin{array}{l}
4 x-30 x+102=24, \\
y=5 x-17,
\end{array}\right. \\
& \left\{\begin{array}{l}
-26 x=-78 \\
y=5 x-17
\end{array}\right. \\
& \left\{\begin{array}{l}
x=3 \\
y=5 \cdot 3-17
\end{array}\right. \\
& \left\{\begin{array}{l}
x=3 \\
y=-2
\end{array}\right.
\end{aligned}\\
&\text { Відповідь: а) }(1 ;-4), \text { б) }(-2 ; 3), \text { в) }(2 ; 5), \text { г) }(3 ;-2) \text {. }
\end{aligned}