Leave superscript mode in Mac Grapher

Mac Grapher has is a keyboard shortcut for entering superscripts: use the ^ key. For instance, you can type x^2 to get the expression *x*2. Once I've entered superscript mode, how do I leave superscript mode? For instance, if I want to enter in the expression *x*2 + 3, what do I type? If I type the characters x^2 + 3 on the keyboard, I get the expression *x*2 + 3, which is not what I wanted. I couldn't find any description of this in the help pages for Grapher.