Номер 308 ГДЗ алгебра 8 клаcс Макарычев

№308.
a) $\sqrt{12+x-7}=3$

$$
\begin{gathered}
\sqrt{5+x}=3 \\
5+x=3^2 \\
5+x=9 \\
x=4
\end{gathered}
$$

6) $\sqrt{5 x-1}-4=6$

$$
\begin{gathered}
\sqrt{5 x-1}=10 \\
5 x-1=10^2 \\
5 x-1=100 \\
5 x=101 \\
x=\frac{101}{5}=20.2
\end{gathered}
$$

в) $16-\sqrt{x-2}=7$

$$
\begin{gathered}
-\sqrt{x-2}=7-16 \\
-\sqrt{x-2}=-9 \\
\sqrt{x-2}=9 \\
x-2=9^2 \\
x-2=81 \\
x=83
\end{gathered}
$$

г) $12-\sqrt{3-6 x}=-2$

$$
\begin{gathered}
-\sqrt{3-6 x}=-2-12 \\
-\sqrt{3-6 x}=-14 \\
\sqrt{3-6 x}=14 \\
3-6 x=14^2 \\
3-6 x=196 \\
-6 x=193 \\
x=-\frac{193}{6}
\end{gathered}
$$


Ответ:
a) $x=4$;
б) $x=20.2$;
в) $x=83$;
г) $x=-\frac{193}{6}$.