Something like "common factor in evidence" , in portuguese

Heres one way to do it using the tikzmark library and then adjusting node positions with the calc library:

documentclass{article}
usepackage{tikz}
usetikzlibrary{tikzmark}
usetikzlibrary{calc}
begin{document}
    [
        (tikzmark{a}ax + tikzmark{b}ay) = tikzmark{c}a(x + y)
        tikz[remember picture, overlay, baseline=0pt] {
            draw[red, thick] ($(pic cs:a) + (0.1, 0.2)$) to[out=90, in=90] ($(pic cs:c) + (0.1, 0.2)$);
            draw[red, thick] ($(pic cs:b) + (0.1, 0.2)$) to[out=90, in=90] ($(pic cs:c) + (0.1, 0.2)$);
        }
    ]
end{document}