\[\boxed{\text{60\ (60).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
Пояснение.
Решение.
\[\textbf{а)}\ 10x^{2} + 5x - 5 = 0\]
\[2x^{2} + x - 1 = 0\]
\[D = 1 + 4 \cdot 2 \cdot 1 = 9\]
\[\ x_{1} = \frac{- 1 + 3}{4} = \frac{1}{2} = 0,5;\ \ \ x_{2} =\]
\[= \frac{- 1 - 3}{4} = - 1.\]
\[Ответ:x = 0,5;\ \ x = 1.\]
\[\textbf{б)} - 2x^{2} + 12x - 18 = 0\ |\ :( - 2)\]
\[x^{2} - 6x + 9 = 0\]
\[(x - 3)^{2} = 0\]
\[x - 3 = 0\]
\[x = 3\]
\[Ответ:x = 3.\]
\[\textbf{в)}\ x^{2} - 2x - 4 = 0\]
\[D_{1} = 1 + 4 = 5\]
\[x_{1,2} = 1 \pm \sqrt{5}.\]
\[Ответ:x = 1 \pm \sqrt{5}.\]
\[\textbf{г)}\ 12x^{2} - 12 = 0\]
\[x^{2} - 1 = 0\ \]
\[x^{2} = 1\]
\[x_{1,2} = \pm 1.\]
\[Ответ:x = \pm 1.\]