I have this picture

If i use `\SetCell[r=2,c=0]{fg=blue}{+}`, I get 
```
\documentclass[border=3.14]{article}
\usepackage[utf8]{vietnam}
\usepackage{tabularray}
\usepackage{ninecolors}
\UseTblrLibrary{amsmath,
	booktabs,
	counter,
	diagbox,
	siunitx,
	varwidth}
\begin{document}

\begin{tblr}{
		cells={mode=dmath,halign=r},
		hline{Y} = {solid},
		colsep = 1mm
	} 
	\SetCell[r=2]{fg=magenta}\times
	& 1 & -2 & 3 \\
	&  & 4 & 7 \\
	\hline
		& 7 & -14 & 21& \\
4 & -8 & 12 & \\
4 & -1 & -1 & 21 
\end{tblr}  

\begin{tblr}{
		cells={mode=dmath,halign=r},
		hline{Y} = {solid},
		colsep = 1mm
	} 
	\SetCell[r=2]{fg=magenta}\times
	& 1 & -2 & 3 \\
	 && 4 & 7 \\
	\hline
	\SetCell[r=2,c=0]{fg=magenta}+
	& 7 & -14 & 21& \\
4 & -8 & 12 & \\
4 & -1 & -2 & 21
\end{tblr}  
\end{document}
```

![image.png](/image?hash=325c96af2a4b395a78fc849cbb9a9711b65eb76c00636fdcd09c5001dcbc81a4)

How can I remove the sign `+` to the left?

![tab.png](/image?hash=fba4053a96b12a83026f1fc9d9cb22d8a7d17d1a0ec5cd0df8020c559f9de8f9)