\(\boxed{\text{341.}\text{\ }\text{еуроки}\text{-}\text{ответы}\text{\ }\text{на}\text{\ }\text{пятёрку}}\)
Пояснение.
Решение.
\[\textbf{а)}\ x^{2} = 30\]
\[x = \sqrt{30}\]
\[x \approx \pm 5,48.\]
\[\textbf{б)}\ 7x^{2} = 10\]
\[x^{2} = \frac{10}{7}\]
\[x = \sqrt{\frac{10}{7}}\]
\[x \approx \pm 1,20.\]
\[\textbf{в)}\ 0,2x^{2} = 3\]
\[x^{2} = 15\]
\[x = \pm \sqrt{15}\]
\[x \approx 3,9.\]
\[Ответ:б).\]