Đáp án:
$\begin{array}{l}
8)M\left( {x;y} \right)\\
\Rightarrow \left\{ \begin{array}{l}
y = - \frac{{{x^2}}}{2}\\
2y = 3x
\end{array} \right.\\
\Rightarrow - \frac{{{x^2}}}{2} = \frac{{3x}}{2}\\
\Rightarrow - {x^2} = 3x\\
\Rightarrow x = - 3\left( {do:x \ne 0} \right)\\
\Rightarrow y = - \frac{9}{2}\\
\Rightarrow M\left( { - 3; - \frac{9}{2}} \right)\\
9)Khi:x = 2 \Rightarrow y = - \frac{{{x^2}}}{4} = - 1\\
\Rightarrow \left( d \right)\,đi\,qua:A\left( {0; - 2} \right);\left( {2; - 1} \right)\\
\Rightarrow \left\{ \begin{array}{l}
- 2 = a.0 + b\\
- 1 = 2a + b
\end{array} \right. \Rightarrow \left\{ \begin{array}{l}
b = - 2\\
a = \frac{1}{2}
\end{array} \right.\\
\Rightarrow \left( d \right):y = \frac{1}{2}x - 2
\end{array}$