# trying to produce a cross diagram with quadratic inputs

I produce something like below but have not able all I have is the nodes but it doesn't work, any help would be appreciated

 \documentclass{article}

\usepackage{tikz}
\usetikzlibrary{arrows.meta}

\begin{document}

\begin{tikzpicture}[
vertex/.style = {shape=circle,draw,minimum size=2em},
edge/.style = {->,-Latex},
]
% Vertices
\node[vertex] (c) at (0,0) {6};
\node[vertex] (a) at (-2,-2) {};
\node[vertex] (b) at (2,-2) {};
\node[vertex] (d) at (0,-3) {6};
\node[vertex] (e) at (-1,-5) {?};
\node[vertex] (f) at (1,-5 {?};
\node[vertex] (g) at (-2,-7) {};
\node[vertex] (h) at (0,-7) {5};
\node[vertex] (i) at (2,-7) {};
\node[vertex] (bx) at (0,-9) {5};
% Edges
\draw[edge, ultra thick] (a) -- (c) node[midway,left] {$\times$}  ;
\draw[edge, ultra thick] (b) -- (c) node[midway,right] {$\times$} ;
\draw[edge, ultra thick] (g) -- (bx) node[midway,left] {$\times$}  ;
\draw[edge, ultra thick] (I) -- (bx) node[midway,right] {$\times$} ;
\draw[edge, ultra thick] (a)t to  node[left] {} (i);

\end{document}


If you know hw to just write the equation to make this work that would be amazing but equally as good if I could just hand type the numbers.