Fill in the blanks with the appropriate word, phrase, or symbol $($ s) from the following list.
$
\begin{array}{lllllll}
\text { reciprocal } & \text { imaginary } & \text { quadratic } & \text { square } & \text { perfect } & \frac{2}{3} & \frac{3}{2} \\
25 & 10 & 100 & \text { one-half } & \text { complex } & \text { binomial }
\end{array}
$
A ______ equation is an equation of the form $a x^{2}+b x+c=0$, where $a, b$, and $c$ are real numbers and $a \neq 0$.