\[\boxed{\text{292\ (292).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[\textbf{а)}\ y = ax^{2}\]
\[точка\ (2;2):\]
\[2 = a \cdot 2^{2}\]
\[a = \frac{2}{4}\ \]
\[a = 0,5.\]
\[\textbf{б)}\ y = ax^{2}\]
\[точка\ (4;\ - 4):\]
\[- 4 = a \cdot 4^{2}\]
\[a = - \frac{4}{16}\]
\[a = - \frac{1}{4} = - 0,25.\]