# Down right to left curved arrows

I am working for homework for my students but I don't know how to make the following curved arrows. Any help is appreciate!

I usually work with the following instructions:

\newcommand\source[1]{%
\tikz[remember picture,baseline,inner sep=0pt] {%
\node [name=source,anchor=base]{$#1$};
}%
\setcounter{target}{0}
}
\newcounter{target}
\newcommand\target[1]{%
\tikz[remember picture,baseline,inner sep=0pt] {%
\node [name=target-\thetarget,anchor=base]{$#1$};
}%
\stepcounter{target}%
}
\newcommand\drawarrows{
\tikz[remember picture, overlay, bend left=45, -latex] {
\foreach \i [evaluate=\i as \n using int(\i-1)] in {1,...,\thetarget} {
\draw (source.north) to (target-\n.north);
}
}
}

But I don't know how to change the direction and position to get the image shown.

Instead of your definitions I would rather try to use tikzmark TikZ library:

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{tikzmark}

\begin{document}
$\frac{x+1}{\tikzmarknode{A}{2}} + \frac{x+1}{\tikzmarknode{B}{3}} \times \tikzmarknode{C}{6} % \begin{tikzpicture}[overlay, remember picture, shorten <=1pt, shorten >=1pt, looseness=1.2, >=latex] \draw[->] (C.south) to [out=240, in=315] (A.south); \draw[->] (C.south) to [out=240, in=315] (B.south); \end{tikzpicture} \vspace{3ex}$
\end{document}

After two compilation the result is:

Addedndum: Arrows heds can be improved by us of packages arrows.meta and bending. About them see TikZ & PGF manual, subsection 16.3.8 Bending and Flexing, page 202:

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{arrows.meta,    % new
bending,        % new
tikzmark}
\usepackage{lipsum}

\begin{document}
$\frac{x+1}{\tikzmarknode{A}{2}} + \frac{x+1}{\tikzmarknode{B}{3}} \times \tikzmarknode{C}{6} % \begin{tikzpicture}[overlay, remember picture, shorten <=1pt, shorten >=1pt, looseness=1.1, >={Stealth[bend]} % changed ] \draw[->] (C.south) to [out=255, in=315] (A.south); \draw[->] (C.south) to [out=255, in=315] (B.south); \end{tikzpicture} \vspace{3ex} % space needed for tikzpicture$
\lipsum[1]
\end{document}

Another solution with pstricks:

\documentclass{article}
\usepackage{pst-node}

\begin{document}

$\frac{x+1}{\pnode[0.5ex, 0]{2}2} + \frac{x+1}{\pnode[0.5ex, 0]{3}3} \times \pnode[1.2ex, 0]{6}{6} % \psset{linewidth=0.5pt, arrows=->, arrowinset=0.12, angleA =-120, nodesep=1.5pt} \nccurve[angleB=-65]{6}{2} \nccurve[angleB=-60]{6}{3}$

\end{document}