a, \(\dfrac{1}{2}x^2=8\)
\(\Rightarrow x^2=8.2=16\)
\(\Rightarrow x^2=4^2\)
\(\Rightarrow x=4\)
b, \(x^2-10< 0\)
\(\Rightarrow x^2< 10\)
\(\text{*}x^2=1\Rightarrow\left[{}\begin{matrix}x=1\\x=-1\end{matrix}\right.\)
\(\text{*}x^2=4\Rightarrow\left[{}\begin{matrix}x=2\\x=-2\end{matrix}\right.\)
\(\text{*}x^2=9\Rightarrow\left[{}\begin{matrix}x=3\\x=-3\end{matrix}\right.\)
