Вправа 21 алгебра Бевз гдз 7 клас
№ 21
а) 8 – 2(3 – х) = 5 – 3(3 – 2х)
8 – 6 + 2х = 5 – 9 + 6х
2 + 2х = –4 + 6х
2x – 6x = –4 – 2
–4x = –6
x = 1,5;
б) 1 + 3(х – 5) = (1 + 3х) – 5х
1 + 3х – 15 = 1 + 3х – 5х
5х = 15
х = 3;
$$
\begin{aligned}
& \text { в) } \frac{2}{3} x-\frac{7}{9}+5=x-\frac{1}{6}(2-6 x) \\
& \frac{2}{3} x-\frac{7}{9}+5=x-\frac{1}{3}+x \\
& \frac{2}{3}-2 x=\frac{7}{9}-5-\frac{1}{3} \\
& -\frac{4}{3} x=-\frac{41}{9} \\
& x=-\frac{41}{9}:\left(-\frac{4}{3}\right) \\
& x=\frac{41}{12} \\
& x=3 \frac{5}{12}
\end{aligned}
$$
вправи поруч
