How to get Beamer Math to look like Article Math

In a LaTeX article, the math characters are more “curvy” than the text characters:

documentclass[12pt]{article}
begin{document}
 $x^2 + y^2 = z^2$
end{document}

In a beamer presentation, the math characters do not have the same curves:

documentclass{beamer}
begin{document}
begin{frame}
 $x^2 + y^2 = z^2$
end{frame}
end{document}

Question

How can I get the beamer math to look just like the article math?

I would prefer if the solution was a single line (that I could place at the top of my LaTeX file) as opposed to something that needs to appear next to every piece of math.

documentclass{beamer}% http://ctan.org/pkg/beamer
usefonttheme[onlymath]{serif}
begin{document}
begin{frame}
 $x^2 + y^2 = z^2$
end{frame}
end{document}

usefonttheme{professionalfonts}

mode<presentation>{...} 

documentclass[mathserif]{beamer}
...